Silicon based drug conjugates and methods of using same

ABSTRACT

Described herein are silicon based conjugates capable of delivering one or more payload moieties to a target cell or tissue. Contemplated conjugates may include a silicon-heteroatom core, one or more optional catalytic moieties, a targeting moiety that permits accumulation of the conjugate within a target cell or tissue, one or more payload moieties (e.g., a therapeutic agent or imaging agent), and two or more non-interfering moieties covalently bound to the silicon-heteroatom core.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/477,721, filed Apr. 3, 2017, which is a continuation of InternationalPatent Application serial number PCT/US2016/032177, filed May 12, 2016,which claims the benefit of, and priority to, U.S. provisionalapplication Ser. No. 62/173,002, filed Jun. 9, 2015, and 62/160,575,filed May 12, 2015, the contents of each of which is hereby incorporatedby reference herein in its entirety.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has been filedelectronically in ASCII format and is hereby incorporated by referencein its entirety. Said ASCII copy, created on Jun. 4, 2019, is namedCOF-033C1_SL.txt and is 1,236 bytes in size.

BACKGROUND

Devices and methods for delivery of desired components to a site ofinterest remain a growing need. A variety of methods and routes ofadministration have been developed to deliver pharmaceuticals ordiagnostics, such as small molecular drugs, imaging agents and/or otherbiologically active compounds (e.g., peptides, hormones, proteins, andenzymes) and many routes of administration are known for deliveringdesired pharmaceuticals to a patient. As greater knowledge is learnedregarding toxicity of drugs and the ability to elicit specific responsesby delivery of a pharmaceutical only to a specific portion of the body,controlled release of pharmaceuticals after their administration hasbecome a highly important area of research.

The therapeutic efficacy of active agents is often limited by theinability to selectively deliver the drugs to the cell. For example,most of the currently available anticancer drugs are highly cytotoxic,and can kill normal cells along with cancerous cells. Thus, when highdoses of drugs are used, there can be severe side effects. As a result,most of the currently used anticancer drugs have a rather limitedtherapeutic index. Such a limit on dosage prevents the completeeradication of cancer cells in a patient, and can lead to recurrence ofthe cancer in many patients. The limit in dosage can also predispose therecurring cancer to drug resistance, thus worsening the prognosis forthe patient. Likewise, the ability to observe selective uptake can leadto selective diagnostics. For example, there is ongoing need forvisualizing the delivery of anticancer agents to tumors via variousimaging techniques just as much as there is a need for delivering acocktail of anticancer agents specifically to those tumors.

More generally, technologies which can specifically deliver drugs toaffected tissues in diseases involving viral, bacterial, inflammatory,metabolic, and neurologic imbalances represent an important therapeuticbreakthrough. Often, therapeutics for these diseases very strictlyrequires a large therapeutic window to be considered for clinical study.Introduction of moieties which deliver these therapeutics directly andspecifically to the diseased tissues or to the disease-causing agentslowers the specificity requirements of the therapeutic itself.

On the surface, antibodies appear to be an ideal coupling partner fortherapeutics, helping to deliver them to very specific tissues. However,most antibody-drug conjugates suffer from some drawbacks. In one case,reliable engineering of the attachments is challenging, with onlystatistical distributions of drugs on the antibody frequently occurring.The potential for cleavage away from the intended target remains withthe linker chemistries employed. In another case, the drug is too wellattached to the antibody and has trouble either cleaving from theantibody or in escaping from the endosome or lysosome once it iscleaved. The end result is either unwanted systemic toxicity or a lackof efficacy. In addition, the drug or payload may not be cleaved orreleased in a uniform manner, thereby resulting in a non-uniformdistribution of the drug or payload. A technology is sorely needed whichallows clean delivery of a uniformly modified antibody to a diseasedtissue whereupon the drug is released and permeates the endosome toreach its therapeutic target. Accordingly, there is an ongoing need fornew therapeutic approaches that permit the selective delivery of activeagents to diseased cells, thereby providing improved therapeuticindices.

SUMMARY

Described herein are silicon based conjugates capable of delivering oneor more payload moieties to a target cell or tissue. Contemplatedconjugates may include a silicon based construct comprising asilicon-heteroatom core having two or more non-interfering moieties eachcovalently bound to the silicon-heteroatom and an optional catalyticmoiety covalently bound directly or indirectly to the silicon-heteroatomcore. Contemplated conjugates may also include one or more targetingmoieties that permit accumulation of the conjugate within a target cellor tissue, one or more payload moieties (e.g., a therapeutic agent,diagnostic, or imaging agent), and two or more non-interfering moietiescovalently bound to the silicon-heteroatom core.

In another embodiment a pharmaceutically acceptable drug conjugate isprovided, comprising: a biological sequence selected from the groupconsisting of an antibody, antibody fragment, protein, or polypeptide,at least one therapeutic agent covalently attached to the biologicalsequence by a spacer containing a cleavable Si-heteroatom moiety (e.g.,a siloxane or silylether moiety). In some embodiments, such a drugconjugate (e.g., an antibody drug conjugate) is substantially stable inaqueous solution having a pH between 7 and 7.5 and/or hydrolyticallycleaves in aqueous solution having a pH less than 7 or greater than 7.5to release the therapeutic agent.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows hydrolysis reaction schemes for three embodiments ofcontemplated conjugates illustrating release of a payload. “TM” is atargeting moiety.

FIG. 2 shows contemplated conjugates containing a scaffold to which atargeting moiety (e.g., a ligand, or an endocytosis agent) and aplurality of payloads (e.g., drugs) are attached. A ligand when showncould be a folic acid, RGD or RGD derivatives, DUPA or DUPA derivatives,an angiopeptide, hyaluronic acid, mannose, or chlorotoxin. FIG. 2discloses SEQ ID NOS 3 and 3, respectively, in order of appearance.

FIGS. 3A and 3B show various non-limiting embodiments for siloxaneconfigurations, with exemplary non-interfering moieties R¹ and R²,catalytic moiety, and exemplary divalent spacers between a payload and atargeting moiety (Ligand).

FIG. 4 shows contemplated conjugates containing the folic acid(targeting moiety), a spacer (PEG units or peptides), a catalytic unit(thiopyrimidine), a disilylether linker, and a payload(sila-camptothecin).

FIG. 5 shows contemplated conjugates containing a platinum(II)-based orplatinum(IV)-based payload.

FIG. 6 shows a contemplated fluorophore-folic acid conjugate.

FIG. 7 shows contemplated fluorophore/quencher-folic acid conjugates.

FIG. 8 shows another contemplated fluorophore-folic acid conjugate usingfluorescein as the fluorophore.

FIGS. 9, 10, and 11 show various mechanisms and end products of aninitial non-pH dependent protease enzyme cleavage, followed bypH-dependent release of a payload.

FIGS. 12 and 13 show exemplary silicon based mAb-drug conjugates.

FIG. 14 indicates an exemplary route to preparation of a disclosedhomogenous siloxane/silylether mAb-drug conjugates.

FIGS. 15A, 15B and 15C describe exemplary routes of payload cleavage forcertain disclosed conjugates having a self-immolating spacer.

FIG. 16 shows contemplated disilylether and silylether conjugatescomprising two targeting moieties and a payload.

FIG. 17 shows various points for attaching connectors on HSP-90 (heatshock protein 90) inhibitor ganetespib or its derivatives.

FIG. 18 shows contemplated HSP-90 ganetespib analogs with camptothecinsilicon-containing conjugates.

FIG. 19 shows contemplated HSP-90 ganetespib analogs with auristatin Fsilicon-containing conjugates.

FIG. 20 shows contemplated HSP-90 ganetespib analogs with DM1silicon-containing conjugates.

FIG. 21 shows contemplated maytansine payload moieties modified withsilicon-containing spacers.

FIG. 22 shows contemplated deacetyl vinblastine payload moietiesmodified with silicon-containing spacers.

FIG. 23 shows contemplated tubulysin payload moieties modified withsilicon-containing spacers.

FIG. 24 shows contemplated auristatin payload moieties modified withsilicon-containing spacers.

FIG. 25 shows contemplated pyrrolobenzodiazepine (PDB) payload moietiesmodified with silicon-containing spacers.

FIG. 26 shows a contemplated silicon based conjugate in which thesilicon-heteroatom core is a siloxane (e.g., —Si—O—Si—).

FIG. 27 shows a contemplated silicon based conjugate having multiplepayload moieties in a payload cassette construct.

DETAILED DESCRIPTION

Described herein are silicon based conjugates capable of delivering oneor more payload moieties to a target cell or tissue. Contemplatedconjugates may include a silicon based construct comprising asilicon-heteroatom core having two or more non-interfering moieties eachcovalently bound to the silicon-heteroatom and an optional catalyticmoiety covalently bound directly or indirectly to the silicon-heteroatomcore. Contemplated conjugates may also include one or more targetingmoieties that permit accumulation of the conjugate within a target cellor tissue, one or more payload moieties (e.g., a therapeutic agent,diagnostic, or imaging agent), and two or more non-interfering moietiescovalently bound to the silicon-heteroatom core. Also described aremethods of making the compositions and methods of administering theconjugates.

For example, provided herein is a silicon based conjugate capable ofdelivering one or more payload moieties to a target cell or tissue,wherein the silicon based conjugate comprises:

-   -   a) a silicon based construct comprising:        -   a silicon-heteroatom core having two or more non-interfering            moieties each covalently bound to the silicon-heteroatom            core such that the presence of the two or more            non-interfering moieties provides that the conjugate is            covalently stable; and        -   an optional catalytic moiety covalently bound directly or            indirectly to the silicon-heteroatom core;    -   b) one or more targeting moieties L, that permits accumulation        of the conjugate within a target cell or tissue, wherein L for        each occurrence is covalently bound directly or indirectly to        the silicon based construct; and    -   one or more payload moieties P, wherein P for each occurrence is        covalently bound directly or indirectly to the silicon based        construct;    -   c) wherein the optional catalytic moiety can transfer a proton        to the silicon-heteroatom core, and provides pH-dependent        payload release of the payload P in vivo or in vitro;    -   or pharmaceutically acceptable salts, cocrystals, stereoisomers,        metabolites, tautomers, solvates, and hydrates thereof.

In some embodiments, a disclosed silicon based conjugate may include twoor more non-interfering moieties which each may be the same ordifferent, and which each may be independently selected to minimizeuntargeted cellular uptake of the conjugate and/or, for example, tooptimize cleavage of the payload P such that P is released into thetarget cell or tissue.

In certain embodiments, a disclosed silicon based conjugate may have asilicon-heteroatom core that may be, for example, a siloxane representedby:

-   -   wherein R¹, R², R³ and R⁴ are each the non-interfering moiety.        In certain embodiments, R¹, R², R³ and R⁴ may each be        independently selected, for example, from C₁₋₄alkyl.

In an embodiment, a disclosed silicon based conjugate may have a siliconbased construct is represented by:

-   -   wherein G¹ is a catalytic moiety and LL¹ is the optional linker        moiety linking the silicon-heteroatom core to the catalytic        moiety. In an embodiment, G¹ may be, for example, a heteroaryl.        In some embodiments, a disclosed catalytic moiety or moieties        may be selected to cleave a Si—O bond of the silicon-heteroatom        core such that the payload moiety, P, is released into the        target cell or tissue.

Silicon based conjugates contemplated herein may be substantially stablein an aqueous solution having a pH of between e.g., about 7 and about7.5 at 25° C., and also hydrolytically cleaves in aqueous solutionhaving a pH less than about 7 or greater than about 7.5 to release thepayload moiety from the conjugate, e.g., upon administration to apatient, the payload P may be cleaved from the conjugate and e.g.,released, delivered or available to a target cell, tissue, or moleculartarget. For example, contemplated conjugates may be stable in certainaqueous solutions (e.g., an in vitro solution or an in vivo solution at25° C. or 37° C. (for example, serum, plasma, whole blood, and/orcytosol)) at a certain pH, and may then be capable of releasing thepayload e.g., at a specific site in vivo. Alternatively, contemplatedconjugates may be capable of releasing the payload in an initially pHindependent manner, e.g., by reductive or hydrolytic cleavage. Forexample, conjugates may release the payload(s) enzymatically (e.g. invivo) as shown in e.g., FIGS. 9-11.

Contemplated silicon based conjugates may include at least one targetingmoiety L (e.g., may include one, two, three or more moieties), which maybe covalently bound for each occurrence to the Si-heteroatom core (e.g.,the siloxane or silylether core through a divalent spacer moiety Y, ormay be directly bonded to e.g. a heteroatom of the silicon-heteroatomcore and/or to a Si atom itself. The payload moieties, P, may be, foreach occurrence, covalently bound to the Si-heteroatom core (e.g.,siloxane or silylether core) through a divalent spacer moiety Y ordirectly to e.g., a heteroatom of the silicon-heteroatom core and/or toa Si atom itself. Exemplary conjugates with one targeting moiety areshown in FIGS. 3A-3B, and exemplary bis-targeting moiety conjugates areshown in FIG. 16.

Divalent spacers (e.g., a moiety Y), when present on the conjugate, maybe selected, for example to maximize targeting moiety L's affinity to atarget cell and/or tissue and in certain embodiments may be selected tooptimize length, rigidity and/or flexibility, or to optimize in vivoparameters and physicochemical properties (such as solubility) of thedrug conjugate. The divalent spacer moiety may contain a pH-sensitivecatalytic moiety which enables the pH-dependent hydrolysis. Exemplaryspacers may include aliphatic and aromatic moieties or a combination ofboth and, for example, may be separately alkylene, alkoxyalkyl, aryl,biaryl, heteroaryl, and vinyl moieties (e.g., are each independentlyselected for each occurrence from the group consisting of: a bond,C₁₋₆alkyl, phenyl, heteroaryl, C₁₋₆alkyoxy, and C₁₋₆alkyoxy-C₁₋₆alkyl,and optionally substituted, by e.g., a substituent selected from thegroup consisting of halogen, C₁₋₆alkyl and C₁₋₆alkyoxy) for eachoccurrence, as shown in e.g., FIGS. 3A and 3B. Exemplary spacers mayalso include peptidic units with natural and non-natural amino acids, orcarbohydrates. In a certain embodiment, a spacer is self-immolating andmay result in pH dependent cleavage and/or reductive cleavage. Specificexemplary conjugates with self-immolating spaces are shown in e.g., FIG.15. Exemplary spacers may include an adaptor moiety which enables theaddition of multiple payloads (e.g., either the same or differentpayloads). Exemplary catalytic moieties may include, but are not limitedto, monocyclic or bicyclic heteroaryl systems, for example, optionallysubstituted pyrroles, furans, thiophenes, imidazoles, pyrazoles,oxazoles, isoxazoles, thiazoles, isothiazoles, pyridines, pyrimidines,triazoles, tetrazoles, etc.

Conjugates can include one, two or more non-interfering moieties (e.g.,R moieties), each covalently bound to the silicon-heteroatom core, suchthat the presence of the two or more non-interfering moieties providesstability and optionally is selected to optimize the hydrolysis profile,e.g., that the conjugate is covalently stable and may also optimize therelease profile of the payload. The non-interfering moieties each may bethe same or different, and each may be independently selected tominimize untargeted cellular uptake of the conjugate and/or optimize thetiming of cleavage of the connection to the payload P such that P isselectively released into the target cell or tissue. For example, one ormore non-interfering moieties may be selected to optimize Si—O bondcleavage such that P is released into the target cell or tissue.Exemplary disclosed conjugates with e.g., a siloxane or a silylethercore and the release of payload under certain pH conditions is shown inFIG. 1, with non-interfering moieties represented by R¹, R², R³, and R⁴.

Conjugates disclosed herein may include targeting moieties (e.g., one,two or three) that each selectively binds or recognizes at least one ofcell surface receptors, transporters, and antigens that areoverexpressed in a disease state. For example, a targeting moiety may becapable of binding to at least one of: a cell surface receptor, acognate ligand of a cell surface receptor, an antigen or a cell wall(e.g., a bacterial cell wall).

For example, targeting moieties may include one or more ligands thatselectively bind or recognize at least one of Folate Receptors, prostatespecific membrane antigen (PSMA), surface antigen in leukemia SAIL,intergrin α_(v)β₃, asialoglycoprotein receptor, hydroxyapatite,delta-like protein-3 DLL3 receptor, receptor dystroglycan,cholescystokinin receptors, somatostatin receptor, onco fetal antigens,receptor tyrosine kinases, GPCRs, GPCRmAB targets, sigma-receptor,transferrin receptor, mannose receptor vitamin receptors, Trop-2, Notchreceptor, CD33, CD44, and CD206. For example, a targeting moiety may beselected from the group consisting of: folic acid its derivatives, DUPAits derivatives, RGD and its derivatives, GPCR mABs, transferrin, G11and analogs thereof which target EGFR, carbohydrates, aptamers,somatostatin analogs, and extracellular ligands that induce receptorinternalization upon binding. For example, targeting moieties may beselected from the group consisting of: small molecules, peptides,peptidomimetics, aptamers, antibodies, and carbohydrates and derivativesthereof. A targeting moiety in certain embodiments is a protein (e.g.,an antibody or antibody fragment), nucleic acid, lipid, oligomer,glycopeptide, polysaccharide, polymer (e.g., a dendrimer), nanoparticle,or any combination thereof. For example, a viral coat protein iscontemplated, as e.g., a cognate ligand of certain cell surfacereceptors.

Silicon based conjugates disclosed herein may include one, two, or morepayloads that may be a therapeutic or diagnostic agent, e.g., may eachselected from the group consisting of: antigens, proteins, cytotoxicagents, metabolic modulators, anti-inflammatory agents, anti-viralagents, pathway modulators, synthetic lethal combinations, siRNA, mRNA,miRNA, endosomal escape enhancers, and imaging agents. For example, eachpayload may be selected from the group consisting of: check-pointinhibitors, kinase inhibitors, proteasome inhibitors, topoisomeraseinhibitors, tubulin inhibitors, rapamycin analogs, auristatin F analogs,maytansinoid analogs, duocarmycin analogs, calicheamicin analogs, DM4analogs, PET tracers, radioactive tracers and fluorophores,photosensitizers, and radiosensitizers, for example, selected fromcamptothecin analogs, doxorubicin analogs, vinca alkaloid analogs,taxane analogs (docetaxel, paclitaxel), rapamycin analogs, platinumbased chemotherapeutics, and tubulysin analogs. The payload moiety of acontemplated conjugate, in some cases, may be a molecule that is, e.g.,modulating cellular pathways by binding to a biomolecule, such as, forexample, a protein or a specific protein domain, a component of abiological cell such as ribosome (composed of proteins and nucleicacids), or an enzyme active site. In some embodiments, the payloadmoiety may be a diagnostic agent.

In an embodiment, provided herein is a silicon based conjugaterepresented by the formula:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a targeting moiety that permits selective accumulation of        the conjugate within a target cell or tissue;    -   P is a payload moiety or payload cassette;    -   R^(P) is P, H, or R⁵;    -   Y¹ is represented by the formula:        -LL¹-G¹-LL²-;    -   Y² is represented by the formula:        -LL³-G²-LL⁴-;    -   G¹ and G² are each optional catalytic moieties each        independently selected from the group consisting of        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl-(wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —NR^(a)—C(O)—C₀₋₆alkyl-,        —C(O)—NR^(a)—C₀₋₆alkyl-, and —NR^(a)—C₀₋₆alkyl-; wherein        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may        optionally be substituted by one or more substituents selected        from the group consisting of halogen, hydroxyl, cyano,        C₁₋₆alkyl, C₁₋₆alkoxy, —COOH, —C(O)—NR^(a)R^(b),        —NR^(a)—C(O)—C₁₋₆alkyl, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H,        —SO₂—NR^(a)R^(b), —NR^(a)—SO₂— C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl;    -   LL¹, LL², LL³ and LL⁴ are spacer moieties each independently        selected from the group consisting of a bond, and C₁₋₂₀alkylene,        wherein one, two, three or four methylene units of C₁₋₂₀alkylene        are optionally and independently replaced by C₃₋₈cycloalkylene,        C₂₋₁₀alkenylene C₂₋₁₀alkynylene, aryl, heteroaryl, amino acids,        polypeptides, —NR^(1Y)—, —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—,        —C(O)—, —OC(O)—, —C(O)O—, —S—, —SO—, —SO₂—, —C(═S)—,        —C(═NR^(1Y))—, —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—;        —(CH₂—CH₂—O)_(s)—, —(O—CH₂—CH₂)_(s)—,        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —S—C₀₋₆alkyl-; —NR^(1Y)—C₁₋₆        alkyl-; —N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—;        —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-;        —N(R^(1Y))SO₂—C₀₋₆alkyl-; —SO₂-heterocyclyl-C₀₋₆alkyl-;        -heterocyclyl-C(O)—; -heterocyclyl-C₀₋₆alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;        —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;        —O—C₁₋₆alkylene-; a natural or unnatural amino acid; a natural        or unnatural oligopeptide; a natural or unnatural polypeptide;        photocleavable motifs; carbohydrates, and a self-immolating        connector; wherein LL¹, LL², LL³ and LL⁴ are optionally        substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic, wherein the        cycloalkyl, haloalkyl, halocycloalkyl, heteroalkyl,        heterocycloalkyl, heterohaloalkyl, heterohalocycloalkyl, aryl,        biaryl, heteroaryl, heterobiaryl, mono or bicyclic heterocyclic        are optionally substituted with one or more substituents        selected from —COOH, urea, amidine, guanidine, sulfonamide,        acylsulfonamide, and sulfonyl amide;    -   s is an integer from 1-15;    -   R¹, R², R³, R⁴ are selected independently for each occurrence        from the group consisting of —Y¹-L, —Y¹—P, H, —OH, OR^(a),        C₁₋₆alkyl, —O—C₁₋₆alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl,        C₃₋₆cycloalkyl, —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid,        heterocyclyl, phenyl, naphthalene, and heteroaryl; wherein        C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b),        heterocyclyl, phenyl, naphthalene, amino acid, and heteroaryl        are optionally substituted by one or more substituents selected        from the group consisting of halogen, cyano, hydroxyl, amino,        —NH(C₁₋₆alkyl), —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆alkyl,        —O—C(O)—C₁₋₆alkyl, —NHC(O)C₁₋₆alkyl, —C(O)NH₂, —C(O)NHC₁₋₆alkyl,        —C(O)N(C₁₋₆alkyl)₂, —NHC(O)CF₃, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl,        —SO₃H, —SO₂—NR^(a)R^(b), —NR^(a)—SO₂—C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl, amidine, guanidine, urea, sulfonamide,        acylsulfonamide, sulfonyl amide, C₁₋₆alkyl, heteroaryl, and        phenyl;    -   R⁵ is selected independently for each occurrence from the group        consisting of H, —OH, OR^(a), C₁₋₆alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, C₁₋₆alkyl,        heteroaryl, and phenyl;    -   or any pairwise combination of Y¹, Y², R¹, R², R³, and R⁴ may,        independently, together with the atoms to which they are        attached, each form a 4-10 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-10 membered heterocyclic        ring is optionally substituted; each ring formed may optionally        be fused to another through a single shared atom or single        shared bond;    -   or R¹ and R², together with the silicon to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, oxo, amino, and        hydroxyl;    -   or Y¹ and R¹, together with the atoms to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted;    -   or Y¹ and R¹, and R¹ and R², together with the atoms to which        they are attached, form a 7-11 membered bicyclic heterocyclic        ring, optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 7-11 membered bicyclic        heterocyclic ring is optionally substituted;    -   or Y¹, R¹, and R², together with the atoms to which they are        attached, form an 11-15 membered tricyclic heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 11-15 membered tricyclic        heterocyclic ring is optionally substituted;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted;    -   or R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted; and    -   wherein the silicon based conjugate is substantially stable in        aqueous solution having a pH of between 7 and 7.5 and        hydrolytically cleaves in aqueous solution having a pH less than        7 or greater than 7.5 to release the payload moiety or payload        cassette from the conjugate.

For example, a contemplated silicon based conjugate disclosed herein maybe represented by the formula:

-   -   wherein G² is a heteroaryl.

FIG. 25 shows a contemplated silicon based conjugate in which thesilicon-heteroatom core is, for example, a siloxane (e.g., —Si—O—Si—).

Also provided herein is a silicon based conjugate capable of deliveringand/or releasing multiple payload moieties, or for example a payloadcassette, to a target cell or tissue. For example, the payload may be apayload cassette. For example, a disclosed payload cassette may allowstoichiometric addition and uniform release of multiple payload moietiesfor each silicon based conjugate. In some embodiments, a payloadcassette may include a branched or linear adaptor moiety having multiplepoints of attachment to which multiple payload moieties are directly orindirectly covalently bound. FIG. 26 shows a contemplated silicon basedconjugate having, for example, multiple payload moieties in a payloadcassette construct.

For example, provided herein is a silicon based conjugate having theformula:

-   -   and pharmaceutically acceptable salts, cocrystals,        stereoisomers, metabolites, tautomers, solvates, and hydrates        thereof, wherein:    -   L is a targeting moiety that permits selective accumulation of        the conjugate within a target cell or tissue;    -   A is an adaptor moiety selected from the group consisting of a        carbon atom, a nitrogen atom, C₃₋₆cycloalkyl, C₃₋₆cycloalkenyl,        phenyl, aryl, biaryl, heteroaryl, heterobiaryl, and mono or        bicyclic heterocyclyl;    -   P is a payload moiety;    -   R^(P) is P, H, or R⁵;    -   Y¹ is represented by the formula:        -LL²-G¹-LL³-;    -   Y² is represented by the formula:        -LL⁴-G²-LL⁵-    -   n is an integer from 2 to 15;    -   m is an integer from 1 to 12;    -   G¹ and G² are each optional catalytic moieties each        independently selected for each occurrence from the group        consisting of -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O— heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, S(O)_(w)-phenyl (wherein        w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may        optionally be substituted by one or more substituents selected        from the group consisting of halogen, hydroxyl, cyano,        C₁₋₆alkyl, C₁₋₆alkoxy, —COOH, —C(O)—O—C₁₋₆alkyl,        —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂—C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl;    -   LL², LL³, LL⁴ and LL⁵ are spacer moieties each independently        selected for each occurrence from the group consisting of a bond        and C₁₋₂₀alkylene, wherein one, two, three or four methylene        units of C₁₋₂₀alkylene are optionally and independently replaced        by C₃₋₈cycloalkylene, C₂₋₁₀alkenylene C₂₋₁₀alkynylene, aryl,        heteroaryl, amino acids, polypeptides, —NR^(1Y)—,        —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—, —C(O)—, —OC(O)—, —C(O)O—,        —S—, —SO—, —SO₂—, —C(═S)—, —C(═NR^(1Y))—,        —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—; —(CH₂—CH₂—O)_(s)—,        —(O—CH₂—CH₂)_(s)—,        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —S—C₀₋₆alkyl-;        —NR^(1Y)—C₁₋₆alkyl-; —N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—;        —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-;        —N(R^(1Y))SO₂—C₀₋₆alkyl-; —SO₂-heterocyclyl-C₀₋₆alkyl-;        -heterocyclyl-C(O)—; -heterocyclyl-C₀₋₆alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;        —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;        —O—C₁₋₆alkylene-; a natural or unnatural amino acid; a natural        or unnatural oligopeptide; a natural or unnatural polypeptide;        photocleavable motifs; carbohydrates, and a self-immolating        connector; wherein LL¹, LL², LL³, LL⁴ and LL⁵ are optionally        substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic, wherein the        cycloalkyl, haloalkyl, halocycloalkyl, heteroalkyl,        heterocycloalkyl, heterohaloalkyl, heterohalocycloalkyl, aryl,        biaryl, heteroaryl, heterobiaryl, mono or bicyclic heterocyclic        are optionally substituted with one or more substituents        selected from —COOH, urea, amidine, guanidine, sulfonamide,        acylsulfonamide, and sulfonyl amide;    -   s is an integer from 1-15;    -   R¹, R², R³, R⁴ are selected independently for each occurrence        from the group consisting of —Y¹-L, —Y¹—P, H, —OH, OR^(a),        C₁₋₆alkyl, —O—C₁₋₆alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl,        C₃₋₆cycloalkyl, —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid,        heterocyclyl, phenyl, naphthalene, and heteroaryl; wherein        C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b),        heterocyclyl, phenyl, naphthalene, amino acid, and heteroaryl        are optionally substituted by one or more substituents selected        from the group consisting of halogen, cyano, hydroxyl, amino,        —NH(C₁₋₆alkyl), —N(C₁₋₆alkyl)₂, oxo, —COOH, —NHC(O)C₁₋₆alkyl,        —C(O)NH₂, —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, —NHC(O)CF₃,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂— C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl, amidine,        guanidine, urea, sulfonamide, acylsulfonamide, sulfonyl amide,        C₁₋₆alkyl, heteroaryl, and phenyl;    -   R⁵ is selected independently for each occurrence from the group        consisting of H, —OH, OR^(a), C₁₋₆alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, C₁₋₆alkyl,        heteroaryl, and phenyl;    -   or any pairwise combination of Y¹, Y², R¹, R², R³, and R⁴ may,        independently, together with the atoms to which they are        attached, each form a 4-10 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-10 membered heterocyclic        ring is optionally substituted; each ring formed may optionally        be fused to another through a single shared atom or single        shared bond;    -   or R¹ and R², together with the silicon to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, oxo, amino, and        hydroxyl;    -   or Y¹ and R¹, together with the atoms to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted;    -   or Y¹ and R¹, and R¹ and R², together with the atoms to which        they are attached, form a 7-11 membered bicyclic heterocyclic        ring, optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 7-11 membered bicyclic        heterocyclic ring is optionally substituted;    -   or Y¹, R¹, and R², together with the atoms to which they are        attached, form an 11-15 membered tricyclic heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 11-15 membered tricyclic        heterocyclic ring is optionally substituted;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted;    -   or R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted; and    -   wherein the silicon based conjugate is substantially stable in        aqueous solution having a pH of between 7 and 7.5 and        hydrolytically cleaves in aqueous solution having a pH less than        7 or greater than 7.5 to release the payload moiety from the        conjugate.

In certain embodiments, A may be a carbon atom. In certain embodiments,n may be 3. In certain embodiments, A may be phenyl. In certainembodiments, n may be 4-15.

For example, a disclosed silicon based conjugate may be branched orlinear and may be represented by the formula:

-   -   wherein m is an integer from 1 to 12.

For example, a disclosed silicon based conjugate may be represented bythe formula:

-   -   wherein G² is a heteroaryl and m is an integer from 1 to 12.

In an embodiment, a disclosed silicon based conjugate may have multiplepayloads which may be different. For example, if two or more payloadmoieties are present on the conjugate, the payload moieties may bedifferent. For example, if three payload moieties are present on theconjugate, the three payload moieties may be different.

In an embodiment, a disclosed silicon based conjugate may have multiplepayloads which may be the same. For example, if two or more payloadmoieties are present on the conjugate, the payload moieties may be thesame. For example, if three payload moieties are present on theconjugate, the three payload moieties may be the same.

In an embodiment, payload moieties of a disclosed silicon basedconjugate may be selected independently for each occurrence to provide asynthetic lethal drug combination capable of effecting death of a targetcell having one or more gene mutations but not of a cell in which theone or more gene mutations are absent. In another embodiment, payloadmoieties of a disclosed silicon based conjugate may be selectedindependently for each occurrence to provide a synthetic lethal drugcombination capable of effecting death of a diseased target tissuecomprised of cells having one or more gene mutations, but not of atissue comprised of cells in which the one or more gene mutations areabsent. Without being limited by theory, use of a disclosed siliconbased conjugate in a synthetic lethal approach may be advantageous incases in which the combination of a mutation and the action of a payloadmoiety causes lethality, whereas the mutation or the action of a payloadmoiety alone are non-lethal. For example, synthetic lethality may arisewhen a combination of mutations in one, two or more genes leads to celldeath, whereas a mutation in only one of these genes does not, and byitself is said to be viable. For example, use of a disclosed siliconbased conjugate in a synthetic lethal approach to, e.g., cancer therapymay provide a means of developing therapies that reduce off-targeteffects of chemotherapies and chemopreventative drugs. For example, adisclosed silicon based conjugate that target synthetic lethal partnersof mutations in, e.g., cancer cells, may not be toxic to normal cells,which may avoid off-target side effects of chemotherapeutics. Forexample, one or more mutations may be associated with a cancer selectedfrom the group consisting of, e.g., renal carcinoma (e.g., VHL clearcell renal carcinoma), mutant KRAS cancers, and breast cancer (e.g.,triple negative breast cancer).

Also provided herein is a silicon based conjugate having multipletargeting moieties, for example, to increase avidity by increasing thenumber of targeting moieties for binding to a cell surface receptor. Incertain embodiments, a disclosed silicon based conjugate may have, forexample, 2 to about 30 targeting moieties. In an embodiment, eachtargeting moiety may be connected to a spacer or an adaptor via covalentbonds. Exemplary spacers and adaptors to which a therapeutic moiety maybe attached include, but are not limited to, peptides, peptoids, PEGs,oligosaccharides, polymers, and oligomers. A spacer or adaptor to atargeting moiety is bound may have configurations such as, for example,oligomeric comb polymer, dendrimer, or dendrimer wedge. In certainembodiments, the multiple targeting moieties may be mixed in differentcombinations to bind to target the heterogeneity of a tumor cell surfacereceptors, tumor microenvironment, and/or organ tissues. In someembodiments, the multiple targeting moieties may be combined withendosomal disrupting agents, cell penetrating peptides (CPP),hydrophilic groups, albumin, etc.

In an embodiment, a disclosed silicon based conjugate having multipletargeting moieties may target a cell, tissue and/or organ including, butnot limited to, for example, those of the kidney, brain, liver, bone,lung, bladder, intestine, cancer, joint, synovial fluid, macrophages,dendritic cells, Th cells, lymphatic system, eye, thymus, dorsal rootganglion (DRG), and muscular system.

In an embodiment, a disclosed silicon based conjugate may have multipletargeting moieties which may be different. For example, if two or moretargeting moieties are present on the conjugate, the targeting moietiesmay be different. For example, if three targeting moieties are presenton the conjugate, the three targeting moieties may be different.

In an embodiment, a disclosed silicon based conjugate may have targetingmoieties which may be the same. For example, if two or more targetingmoieties are present on the conjugate, the targeting moieties may be thesame. For example, if three targeting moieties are present on theconjugate, the three targeting moieties may be the same.

For example, a disclosed silicon based conjugate may be represented bythe formula:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a targeting moiety that permits selective accumulation of        the conjugate within a target cell or tissue;    -   A is an adaptor moiety selected from the group consisting of a        carbon atom, a nitrogen atom, C₃₋₆cycloalkyl, C₃₋₆cycloalkenyl,        phenyl, aryl, biaryl, heteroaryl, heterobiaryl, and mono or        bicyclic heterocyclyl;    -   P is a payload moiety;    -   R^(P) is P, H, or R⁵;    -   Y¹ is represented by the formula:        -LL²-G¹-LL³-;    -   Y² is represented by the formula:        -LL⁴-G²-LL⁵-    -   n is an integer from 2 to 15;    -   G¹ and G² are each optional catalytic moieties each        independently selected from the group consisting of a bond,        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, may optionally be substituted by one or        more substituents selected from the group consisting of halogen,        hydroxyl, cyano, C₁₋₆alkyl, C₁₋₆alkoxy, —COOH,        —C(O)—O—C₁₋₆alkyl, —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂— C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl;    -   LL¹, LL², LL³, LL⁴ and LL⁵ are spacer moieties each        independently selected for each occurrence from the group        consisting of a bond and C₁₋₂₀alkylene, wherein one, two, three        or four methylene units of C₁₋₂₀alkylene are optionally and        independently replaced by C₃₋₈cycloalkylene, C₂₋₁₀alkenylene        C₂₋₁₀alkynylene, aryl, heteroaryl, amino acids, polypeptides,        —NR^(1Y)—, —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—, —C(O)—,        —OC(O)—, —C(O)O—, —S—, —SO—, —SO₂—, —C(═S)—, —C(═NR^(1Y))—,        —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—; —(CH₂—CH₂—O)_(s)—,        —(O—CH₂—CH₂)_(s)—,        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —S—C₀₋₆alkyl-; —NR^(1Y)—C₁₋₆        alkyl-; —N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—;        —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-;        —N(R^(1Y))SO₂—C₀₋₆alkyl-; —SO₂-heterocyclyl-C₀₋₆alkyl-;        -heterocyclyl-C(O)—; -heterocyclyl-C_(m)alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;        —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;        —O—C₁₋₆alkylene-; a natural or unnatural amino acid; a natural        or unnatural oligopeptide; a natural or unnatural polypeptide;        photocleavable motifs; carbohydrates, and a self-immolating        connector; wherein LL¹, LL², LL³, LL⁴ and LL⁵ are optionally        substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic, wherein the        cycloalkyl, haloalkyl, halocycloalkyl, heteroalkyl,        heterocycloalkyl, heterohaloalkyl, heterohalocycloalkyl, aryl,        biaryl, heteroaryl, heterobiaryl, mono or bicyclic heterocyclic        are optionally substituted with one or more substituents        selected from —COOH, urea, amidine, guanidine, sulfonamide,        acylsulfonamide, and sulfonyl amide;    -   s is an integer from 1-15;    -   R¹, R², R³, R⁴ are selected independently for each occurrence        from the group consisting of —Y¹-L, —Y¹—P, H, —OH, OR^(a),        C₁₋₆alkyl, —O—C₁₋₆alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl,        C₃₋₆cycloalkyl, —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid,        heterocyclyl, phenyl, naphthalene, and heteroaryl; wherein        C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b),        heterocyclyl, phenyl, naphthalene, amino acid, and heteroaryl        are optionally substituted by one or more substituents selected        from the group consisting of halogen, cyano, hydroxyl, amino,        —NH(C₁₋₆alkyl), —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆alkyl,        —O—C(O)—C₁₋₆alkyl, —NHC(O)C₁₋₆alkyl, —C(O)NH₂, —C(O)NHC₁₋₆alkyl,        —C(O)N(C₁₋₆alkyl)₂, —NHC(O)CF₃, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl,        —SO₃H, —SO₂—NR^(a)R^(b), —NR^(a)—SO₂—C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl, amidine, guanidine, urea, sulfonamide,        acylsulfonamide, sulfonyl amide, C₁₋₆alkyl, heteroaryl, and        phenyl;    -   R⁵ is selected independently for each occurrence from the group        consisting of H, —OH, OR^(a), C₁₋₆alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, C₁₋₆alkyl,        heteroaryl, and phenyl;    -   or any pairwise combination of Y¹, Y², R¹, R², R³, and R⁴ may,        independently, together with the atoms to which they are        attached, each form a 4-10 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-10 membered heterocyclic        ring is optionally substituted; each ring formed may optionally        be fused to another through a single shared atom or single        shared bond;    -   or R¹ and R², together with the silicon to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, oxo, amino, and        hydroxyl;    -   or Y¹ and R¹, together with the atoms to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted;    -   or Y¹ and R¹, and R¹ and R², together with the atoms to which        they are attached, form a 7-11 membered bicyclic heterocyclic        ring, optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 7-11 membered bicyclic        heterocyclic ring is optionally substituted;    -   or Y¹, R¹, and R², together with the atoms to which they are        attached, form an 11-15 membered tricyclic heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 11-15 membered tricyclic        heterocyclic ring is optionally substituted;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted;    -   or R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted; and    -   wherein the silicon based conjugate is substantially stable in        aqueous solution having a pH of between 7 and 7.5 and is        hydrolytically cleaves in aqueous solution having a pH less than        7 or greater than 7.5 to release the payload moiety from the        conjugate.

In certain embodiments, A may be a carbon atom. In certain embodiments,n may be 3. In certain embodiments, A may be phenyl. In certainembodiments, n may be 4-15.

For example, a disclosed silicon based conjugate may be represented bythe formula:

For example, a disclosed silicon based conjugate may be represented bythe formula:

-   -   wherein G² is a heteroaryl.

In an embodiment, a disclosed silicon based conjugate may be representedby the formula:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a targeting moiety that permits selective accumulation of        the conjugate within a target cell or tissue;    -   A¹ and A² are each adaptor moieties each independently selected        from the group consisting of a carbon atom, a nitrogen atom,        C₃₋₆cycloalkyl, C₃₋₆cycloalkenyl, phenyl, aryl, biaryl,        heteroaryl, heterobiaryl, and mono or bicyclic heterocyclyl;    -   P is a payload moiety;    -   R^(P) is P, H, or R⁵;    -   Y¹ is represented by the formula:        LL²-G¹-LL³-;    -   Y² is represented by the formula:        -LL⁴-G²-LL⁵-    -   n is an integer from 2 to 15;    -   m is an integer from 2 to 15;    -   G¹ and G² are each optional catalytic moieties each        independently selected for each occurrence from the group        consisting of a bond, -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, —O—C(O)—C₀₋₆ alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, may optionally be substituted by one or        more substituents selected from the group consisting of halogen,        hydroxyl, cyano, C₁₋₆alkoxy, —COOH, —C(O)—NR^(a)R^(b),        —NR^(a)—C(O)—C₁₋₆alkyl, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H,        —SO₂—NR^(a)R^(b), —NR^(a)—SO₂— C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl;    -   LL¹, LL², LL³, LL⁴ and LL⁵ are spacer moieties each        independently selected for each occurrence from the group        consisting of a bond and C₁₋₂₀alkylene, wherein one, two, three        or four methylene units of C₁₋₂₀alkylene are optionally and        independently replaced by C₃₋₈cycloalkylene, C₂₋₁₀alkenylene        C₂₋₁₀alkynylene, aryl, heteroaryl, amino acids, polypeptides,        —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—, —C(O)—, —OC(O)—, —C(O)O—,        —S—, —SO—, —SO₂—, —C(═S)—, —C(═NR^(1Y))—,        —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—; —(CH₂—CH₂—O)_(s)—,        —(O—CH₂—CH₂)_(s)—,        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —NR^(1Y)—C₁₋₆alkyl-;        —N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—;        —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-;        —N(R^(1Y))SO₂—C₀₋₆alkyl-; —SO₂-heterocyclyl-C₀₋₆alkyl-;        -heterocyclyl-C(O)—; -heterocyclyl-C₀₋₆alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;        —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;        —O—C₁₋₆alkylene-; a natural or unnatural amino acid; a natural        or unnatural oligopeptide; a natural or unnatural polypeptide;        photocleavable motifs; carbohydrates, and a self-immolating        connector; wherein LL¹, LL², LL³, LL⁴ and LL⁵ are optionally        substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic, wherein the        cycloalkyl, haloalkyl, halocycloalkyl, heteroalkyl,        heterocycloalkyl, heterohaloalkyl, heterohalocycloalkyl, aryl,        biaryl, heteroaryl, heterobiaryl, mono or bicyclic heterocyclic        are optionally substituted with one or more substituents        selected from —COOH, urea, amidine, guanidine, sulfonamide,        acylsulfonamide, and sulfonyl amide;    -   s is an integer from 1-15;    -   R¹, R², R³, R⁴ are selected independently for each occurrence        from the group consisting of —Y¹-L, —Y¹—P, H, —OH, OR^(a),        C₁₋₆alkyl, —O—C₁₋₆alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl,        C₃₋₆cycloalkyl, —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid,        heterocyclyl, phenyl, naphthalene, and heteroaryl; wherein        C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b),        heterocyclyl, phenyl, naphthalene, amino acid, and heteroaryl        are optionally substituted by one or more substituents selected        from the group consisting of halogen, cyano, hydroxyl, amino,        —NH(C₁₋₆alkyl), —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆alkyl,        —O—C(O)—C₁₋₆alkyl, —NHC(O)C₁₋₆alkyl, —C(O)NH₂, —C(O)NHC₁₋₆alkyl,        —C(O)N(C₁₋₆alkyl)₂, —NHC(O)CF₃, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl,        —SO₃H, —SO₂—NR^(a)R^(b), —NR^(a)—SO₂— C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl, amidine, guanidine, urea, sulfonamide,        acylsulfonamide, sulfonyl amide, C₁₋₆alkyl, heteroaryl, and        phenyl;    -   R⁵ is selected independently for each occurrence from the group        consisting of H, —OH, OR^(a), C₁₋₆alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, C₁₋₆alkyl,        heteroaryl, and phenyl;    -   or any pairwise combination of Y¹, Y², R¹, R², R³, and R⁴ may,        independently, together with the atoms to which they are        attached, each form a 4-10 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-10 membered heterocyclic        ring is optionally substituted; each ring formed may optionally        be fused to another through a single shared atom or single        shared bond;    -   or R¹ and R², together with the silicon to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, oxo, amino, and        hydroxyl;    -   or Y¹ and R¹, together with the atoms to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted;    -   or Y¹ and R¹, and R¹ and R², together with the atoms to which        they are attached, form a 7-11 membered bicyclic heterocyclic        ring, optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 7-11 membered bicyclic        heterocyclic ring is optionally substituted;    -   or Y¹, R¹, and R², together with the atoms to which they are        attached, form an 11-15 membered tricyclic heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 11-15 membered tricyclic        heterocyclic ring is optionally substituted;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted;    -   or R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted; and    -   wherein the silicon based conjugate is substantially stable in        aqueous solution having a pH of between 7 and 7.5 and is        hydrolytically cleaves in aqueous solution having a pH less than        7 or greater than 7.5 to release the payload moiety from the        conjugate.

In certain embodiments, A¹ and A² each may be a carbon atom. In certainembodiments, m and n each may be 3.

For example, a disclosed silicon based conjugate may be represented bythe formula:

-   -   wherein G² is a heteroaryl.

In certain embodiments, a disclosed silicon based conjugate may beassembled through synthetic transformations well known to one skilled inthe art. For example, a payload moiety may be attached to a divalentspacer moiety, and/or a targeting moiety may be attached to a divalentspacer moiety, synthetic transformations well known to one skilled inthe art of organic synthesis. Exemplary transformations may include, butare not limited to, amide bond formation, conjugate addition of anucleophile onto a succinimide or maleimide, “click” type reaction(i.e., an azide-alkyne cycloaddition, Huisgen cycloaddition),aldehyde/ketone condensation, oximes (aldoxime, ketoxime), imine(aldimine, ketimine, sulfinyl imine), hydrazone (acyl hydrazone,carboxyl hydrazone, semi-carbazone), ketal/acetal, orthoester, reductiveamination, pyrazole formation (1,3-dicarbonyl+hydrazine),Pictet-Spengler (hydrazino & hydroxyl/alkoxy-amino), strain-promotedalkyne-nitrone cycloaddition, photoinduced tetrazole-alkenecycloaddition, Staudinger ligation, Diels-Alder, Michael addition(thiol+α,β-unsaturated carbonyl), Caddick Michael addition/elimination(thiol+α,β-unsaturated bromo-carbonyl), amide, carbamate,acylsulfonamide, sulfonylamide, thiourea, urea, metal-catalyzed couplingreactions (Pd, Rh, Ru, Re, Cu, Mn, Fe, etc.), or additions to squaricacid ester amides. In an embodiment, a silicon based conjugate isprovided that is represented by formula A or B:Z—(Si—(Y_(y)—X)₃)₂  [A]Si(Y_(y)—X)_(t)—(Z—Y_(y)—X)_(q)  [B]wherein

-   -   y, for each occurrence of Y, is 0 or 1;    -   q is 0, 1, 2, 3, or 4;    -   t is (4-q);    -   Z is an optionally substituted heteroatom;    -   Y is a divalent spacer moiety; which may optionally include a        catalytic moiety G;    -   X is independently selected for each occurrence from P, a        payload moiety; L, a targeting moiety, and R, such that at least        one P and one L is present;    -   R, for each occurrence, may the same or different and is a        non-interfering moiety; and    -   G is an optional catalytic moiety selected from the group        consisting of -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-(wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —C(O)—NR^(a)—C₀₋₆alkyl-, and —NR^(a)—C₀₋₆alkyl-; wherein        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may        optionally be substituted by one or more substituents selected        from the group consisting of halogen, hydroxyl, cyano,        C₁₋₆alkyl, C₁₋₆alkoxy, —COOH, —C(O)—O—C₁₋₆alkyl,        —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂— C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl.

In an embodiment, a silicon based conjugate is provided that is an acid-or base-cleavable silylether conjugate having the formula:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a targeting moiety that permits selective accumulation of        the conjugate within a target cell or tissue;    -   P is a payload moiety or payload cassette;    -   R^(P) is H, P, or R³;    -   Y¹ is represented by the formula:        -LL¹-G¹-LL²-;    -   Y² is represented by the formula:        -LL³-G²-LL⁴-    -   G¹ and G² are each optional catalytic moieties each        independently selected from the group consisting of        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl-(wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —NR^(a)—C(O)—C₀₋₆alkyl-,        —C(O)—NR^(a)—C₀₋₆alkyl-, and —NR^(a)—C₀₋₆alkyl-; wherein        -heteroaryl-, —O-heteroaryl-, —NR^(a)— heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may        optionally be substituted by one or more substituents selected        from the group consisting of halogen, hydroxyl, cyano,        C₁₋₆alkyl, C₁₋₆alkoxy, —COOH, —C(O)—NR^(a)R^(b),        —NR^(a)—C(O)—C₁₋₆alkyl, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H,        —SO₂—NR^(a)R^(b), —NR^(a)—SO₂— C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl;    -   LL¹, LL², LL³ and LL⁴ are spacer moieties each independently        selected from the group consisting of a bond, and C₁₋₂₀alkylene,        wherein one, two, three or four methylene units of C₁₋₂₀alkylene        are optionally and independently replaced by C₃₋₈cycloalkylene,        C₂₋₁₀alkenylene C₂₋₁₀alkynylene, aryl, heteroaryl, amino acids,        polypeptides, —NR^(1Y)—, —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—,        —C(O)—, —OC(O)—, —C(O)O—, —S—, —SO—, —SO₂—, —C(═S)—,        —C(═NR^(1Y))—, —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—;        —(CH₂—CH₂—O)_(s)—, —(O—CH₂—CH₂)_(s)—,        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —NR^(1Y)—C₁₋₆ alkyl-;        —N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—;        —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-;        —N(R^(1Y))SO₂—C₀₋₆alkyl-; —SO₂-heterocyclyl-C₀₋₆alkyl-;        -heterocyclyl-C(O)—; -heterocyclyl-C₀₋₆alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;        —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;        —O—C₁₋₆alkylene-; a natural or unnatural amino acid; a natural        or unnatural oligopeptide; a natural or unnatural polypeptide;        photocleavable motifs; carbohydrates, and a self-immolating        connector; wherein LL¹, LL², LL³ and LL⁴ are optionally        substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic, wherein the        cycloalkyl, haloalkyl, halocycloalkyl, heteroalkyl,        heterocycloalkyl, heterohaloalkyl, heterohalocycloalkyl, aryl,        biaryl, heteroaryl, heterobiaryl, mono or bicyclic heterocyclic        are optionally substituted with one or more substituents        selected from —COOH, urea, amidine, guanidine, sulfonamide,        acylsulfonamide, and sulfonyl amide; and    -   s is an integer from 1-15;    -   R¹ and R² are selected independently for each occurrence from        the group consisting of —Y¹-L, —Y¹—P, H, —OH, OR^(a), C₁₋₆alkyl,        —O—C₁₋₆alkyl, C₂₋₆ alkenyl, C₂₋₆ alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid, and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, C₁₋₆alkyl,        heteroaryl, and phenyl;    -   R³ is selected independently for each occurrence from the group        consisting of H, —OH, OR^(a), C₁₋₆alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, C₁₋₆alkyl,        heteroaryl, and phenyl;    -   or any pairwise combination of Y¹, Y², R¹, and R² may,        independently, together with the atoms to which they are        attached, each form a 4-10 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-10 membered heterocyclic        ring is optionally substituted; each ring formed may optionally        be fused to another through a single shared atom or single        shared bond;    -   or R¹ and R², together with the silicon to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted;    -   or any two or more substituents covalently bonded to the Si may        together optionally form a 4-8 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-8 membered heterocyclic        ring is optionally substituted; provided that all attached P can        be released from the conjugate under conditions suitable for        selective release into a targeted cell or tissue;    -   or Y¹ and R¹, or Y¹ and R², together with the atoms to which        they are attached, form a 4-8 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-8 membered heterocyclic        ring is optionally substituted;    -   or Y¹ and R¹, and R¹ and R², together with the atoms to which        they are attached, form a 7-11 membered bicyclic heterocyclic        ring, optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 7-11 membered bicyclic        heterocyclic ring is optionally substituted;    -   or Y¹, R¹, and R², together with the atoms to which they are        attached, form an 11-15 membered tricyclic heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 11-15 membered tricyclic        heterocyclic ring is optionally substituted;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        heteroaryl, and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl,        heteroaryl, and phenyl may be optionally substituted;    -   or R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted;    -   wherein the silylether is substantially stable in aqueous        solution having a pH of between 7 and 7.5 and hydrolytically        cleaves in aqueous solution having a pH less than 7 or greater        than 7.5 to release the payload moiety or payload cassette from        the conjugate.

For example, provided herein is an acid- or base-cleavable silyletherconjugate selected from the group consisting of:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a targeting moiety that permits selective accumulation of        the conjugate within a target cell or tissue;    -   P is a payload moiety or payload cassette;    -   R^(P) is P or R³;    -   Y¹ is represented by the formula:        -LL¹-G¹-LL²-;    -   Y² is represented by the formula:        -LL³-G²-LL⁴-;    -   Y³ is represented by the formula:        -LL⁵-G³-LL⁶-    -   G¹, G² and G³ are each optional catalytic moieties each        independently selected from the group consisting of        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl-(wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, may optionally be substituted by one or        more substituents selected from the group consisting of halogen,        hydroxyl, cyano, C₁₋₆alkyl, C₁₋₆alkoxy, —COOH,        —C(O)—O—C₁₋₆alkyl, —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂— C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl;    -   LL¹, LL², LL³, LL⁴, LL⁵ and LL⁶ are spacer moieties each        independently selected from the group consisting of a bond, and        C₁₋₂₀alkylene, wherein one, two, three or four methylene units        of C₁₋₂₀alkylene are optionally and independently replaced by        C₃₋₈cycloalkylene, C₂₋₁₀alkenylene C₂₋₁₀alkynylene, aryl,        heteroaryl, amino acids, polypeptides, —NR^(1Y)—,        —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—, —C(O)—, —OC(O)—, —C(O)O—,        —S—, —SO—, —SO₂—, —C(═S)—, —C(═NR^(1Y))—,        —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—; —(CH₂—CH₂—O)_(s)—,        —(O—CH₂—CH₂)_(s)—,        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —S—C₀₋₆alkyl-; —NR^(1Y)—C₁₋₆        alkyl-; —N(C₁₋₃ alkyl)-C₁₋₆alkyl-NH—C(O)—; —NH—C₁₋₆ alkyl-N(C₁₋₃        alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-; —N(R^(1Y))SO₂—C₀₋₆alkyl-;        —SO₂-heterocyclyl-C₀₋₆alkyl-; -heterocyclyl-C(O)—;        -heterocyclyl-C_(m)alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;        —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;        —O—C₁₋₆alkylene-; a natural or unnatural amino acid; a natural        or unnatural oligopeptide; a natural or unnatural polypeptide;        photocleavable motifs; carbohydrates, and a self-immolating        connector; wherein LL¹, LL², LL³, LL⁴, LL⁵ and LL⁶ are        optionally substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic; and    -   s is an integer from 1-15;    -   R¹ is selected independently for each occurrence from the group        consisting of —Y¹-L, —Y¹—P, H, —OH, OR^(a), C₁₋₆alkyl,        —O—C₁₋₆alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl, —C₁₋₆        alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl, phenyl,        naphthalene, and heteroaryl; wherein C₁₋₆alkyl, C₂₋₆alkenyl,        C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl, naphthalene,        amino acid, and heteroaryl are optionally substituted by one or        more substituents selected from the group consisting of halogen,        cyano, hydroxyl, amino, —NH(C₁₋₆alkyl), —N(C₁₋₆alkyl)₂, oxo,        —COOH, —C(O)O—C₁₋₆, —C(O)NH₂, —C(O)NHC₁₋₆alkyl,        —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea, sulfonamide,        acylsulfonamide, sulfonyl amide, C₁₋₆alkyl, heteroaryl, and        phenyl;    -   or any pairwise combination of Y¹, Y², Y³ and R¹ may,        independently, together with the atoms to which they are        attached, each form a 4-10 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-10 membered heterocyclic        ring is optionally substituted; each ring formed may optionally        be fused to another through a single shared atom or single        shared bond;    -   or Y¹ and R¹, together with the atoms to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, oxo, amino, and        hydroxyl;    -   R³ is selected independently for each occurrence from the group        consisting of H, —OH, OR^(a), C₁₋₆alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, C₁₋₆alkyl,        heteroaryl, and phenyl;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted by one or more substituents;    -   or R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted;    -   wherein the silylether is substantially stable in aqueous        solution having a pH of between 7 and 7.5 and hydrolytically        cleaves in aqueous solution having a pH less than 7 or greater        than 7.5 to release the payload moiety or payload cassette from        the conjugate.

Also provided herein, in an embodiment, is a cleavable silyletherconjugate selected from the group consisting of:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a targeting moiety that permits selective accumulation of        the conjugate within a target cell or tissue;    -   P is a payload moiety or payload cassette;    -   R^(P) is H, P, or R³;    -   Y¹ is represented by the formula:        -LL¹-G¹-LL²-;    -   Y² is represented by the formula:        -LL³-G²-LL⁴-;    -   G¹ and G² are each optional catalytic moieties each        independently selected from the group consisting of        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl-(wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, may optionally be substituted by one or        more substituents selected from the group consisting of halogen,        hydroxyl, cyano, C₁₋₆alkyl, C₁₋₆alkoxy, —COOH,        —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂—C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆ alkyl;    -   LL¹, LL², LL³ and LL⁴ are spacer moieties each independently        selected from the group consisting of a bond, and C₁₋₂₀alkylene,        wherein one, two, three or four methylene units of C₁₋₂₀alkylene        are optionally and independently replaced by C₃₋₈cycloalkylene,        C₂₋₁₀alkenylene C₂₋₁₀alkynylene, aryl, heteroaryl, amino acids,        polypeptides, —NR^(1Y)—, —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—,        —C(O)—, —OC(O)—, —C(O)O—, —S—, —SO—, —SO₂—, —C(═S)—,        —C(═NR^(1Y))—, —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—;        —(CH₂—CH₂—O)_(s)—, —(O—CH₂—CH₂)_(s)—,        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —NR^(1Y)—C₁₋₆ alkyl-;        —N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—;        —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-;        —N(R^(1Y))SO₂—C₀₋₆alkyl-; —SO₂-heterocyclyl-C₀₋₆alkyl-;        -heterocyclyl-C(O)—; -heterocyclyl-C₀₋₆alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;        —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;        —O—C₁₋₆alkylene-; a natural or unnatural amino acid; a natural        or unnatural oligopeptide; a natural or unnatural polypeptide;        photocleavable motifs; carbohydrates, and a self-immolating        connector; wherein LL¹, LL², LL³ and LL⁴ are optionally        substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆ alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic; and    -   s is an integer from 1-15;    -   R¹ and R² are selected independently for each occurrence from        the group consisting of —Y¹-L, Y¹—P, H, —OH, OR^(a), C₁₋₆ alkyl,        —O—C₁₋₆ alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl,        —C₁₋₆alkyl-NR^(a)R^(b), α- or β-amino acid, heterocyclyl,        phenyl, naphthalene, and heteroaryl; wherein C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,        naphthalene, amino acid, and heteroaryl are optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, hydroxyl, amino, —NH(C₁₋₆alkyl),        —N(C₁₋₆alkyl)₂, oxo, —COOH, —C(O)O—C₁₋₆, —C(O)NH₂,        —C(O)NHC₁₋₆alkyl, —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea,        sulfonamide, acylsulfonamide, sulfonyl amide, heteroaryl, and        phenyl;    -   R³ is selected independently for each occurrence from the group        consisting of H, —OH, OR^(a), C₁₋₆alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl, C₁₋₆alkyl NR^(a)R^(b),        α- or β-amino acid, heterocyclyl, phenyl, naphthalene, and        heteroaryl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl,        R^(a), R^(b), heterocyclyl, phenyl, naphthalene, amino acid and        heteroaryl are optionally substituted by one or more        substituents selected from the group consisting of halogen,        cyano, hydroxyl, amino, —NH(C₁₋₆alkyl), —N(C₁₋₆alkyl)₂, oxo,        —COOH, —C(O)O—C₁₋₆, —C(O)NH₂, —C(O)NHC₁₋₆alkyl,        —C(O)N(C₁₋₆alkyl)₂, amidine, guanidine, urea, sulfonamide,        acylsulfonamide, sulfonyl amide, C₁₋₆alkyl, heteroaryl, and        phenyl;    -   or any pairwise combination of Y¹, Y², R¹, and R² may,        independently, together with the atoms to which they are        attached, each form a 4-10 membered heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 4-10 membered heterocyclic        ring is optionally substituted; each ring formed may optionally        be fused to another through a single shared atom or single        shared bond;    -   or R¹ and R², together with the silicon to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted;    -   or Y¹ and R¹, together with the atoms to which they are        attached, form a 4-8 membered heterocyclic ring, optionally        containing one or more additional heteroatoms selected from O,        S, or N; wherein the 4-8 membered heterocyclic ring is        optionally substituted;    -   or Y¹ and R¹, and R¹ and R², together with the atoms to which        they are attached, form a 7-11 membered bicyclic heterocyclic        ring, optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 7-11 membered bicyclic        heterocyclic ring is optionally substituted by one or more        substituents selected from the group consisting of halogen,        cyano, oxo, amino, and hydroxyl;    -   or Y¹, R¹, and R², together with the atoms to which they are        attached, form an 11-15 membered tricyclic heterocyclic ring,        optionally containing one or more additional heteroatoms        selected from O, S, or N; wherein the 11-15 membered tricyclic        heterocyclic ring is optionally substituted;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted;    -   or R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted;    -   wherein the silylether is substantially stable in aqueous        solution having a pH of at least 7 and hydrolytically cleaves in        aqueous solution having a pH less than 7 to release the payload        moiety or payload cassette from the conjugate.

In certain embodiments, a payload may be capable of binding anintracellular biomolecular target.

Exemplary silicon based conjugates may be selected from the groupconsisting of:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is, for each example, a moiety capable of binding to a cell        surface receptor;    -   Y¹¹, Y²² and Y³³ are each independently a bond or spacer;    -   P¹ is a first payload moiety;    -   P² is a second payload moiety;    -   Y¹¹, Y²² and Y³³ are each independently selected from the group        consisting of a bond, C₁₋₂₀alkylene, wherein one, two, or three        or four methylene units of the hydrocarbon chain are optionally        and independently replaced by C₃₋₈cycloalkylene,        C₂₋₁₀alkenylene, C₂₋₁₀alkynylene, amino acids, polypeptides,        —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—, —C(O)—, —OC(O)—, —C(O)O—,        —SO—, —SO₂—, —C(═S)—, —C(═NR^(1Y))—, phenyl, naphthyl, or a mono        or bicyclic heterocycle ring; —NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—;        —(CH₂—CH₂—O)_(s)—; —(O—CH₂—CH₂)_(s)—;        —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;        —(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —S—C₀₋₆alkyl-;        —NR^(1Y)—C₁₋₆alkyl-; —N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—;        —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—; —SO₂—NR^(1Y)—C₀₋₆alkyl-;        —N(R^(1Y))SO₂—C₀₋₆alkyl-, —SO₂-heterocyclyl-C₀₋₆alkyl-;        -heterocyclyl-C(O)—; -heterocyclyl-C_(m)alkyl-NR^(1Y)—C(O)—;        —NR^(1Y)—C₀₋₆alkylene-heterocyclene-C(O)—;        —O—C₁₋₆alkylene-C(O)—; —O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—;        —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—; —O—C₁₋₆alkylene-; a natural or        unnatural amino acid; a natural or unnatural oligopeptide; a        natural or unnatural polypeptide; photocleavable motifs; and a        self-immolating connector; wherein Y¹¹ and Y²² and Y³³ are        optionally substituted;    -   wherein, independently for each occurrence, R^(1Y) is selected        from the group consisting of H, C₁₋₆alkyl, cycloalkyl,        haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,        heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,        heterobiaryl, mono or bicyclic heterocyclic; and    -   s is an integer from 1-15;    -   R¹ is selected independently for each occurrence from the group        consisting of H, Y¹¹—P, Y¹¹-L, —OH, C₁₋₆ alkyl, —O—C₁₋₆alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, —C₁₋₆alkyl-NR^(a)R^(b),        heterocyclyl, phenyl, naphthalene, and heteroaryl; wherein        C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b),        heterocyclyl, phenyl, naphthalene, and heteroaryl, are        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, hydroxyl, amino,        C₁₋₆alkyl, heteroaryl, and phenyl;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, oxo, and hydroxyl; or    -   R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, oxo, amino, and hydroxyl;    -   R^(W) is selected from the group consisting of a bond,        —C₁₋₄alkyl-, —O—C₁₋₄alkyl-, —N(R^(a))—C₁₋₄alkyl-,        —C₁₋₄alkyl-C(O)—, —C(O)C₁₋₄alkyl-, —C₁₋₄alkyl-O—C(O)—,        —C(O)—O—C₁₋₄alkyl-, —NR^(a)—C(O)—, —C₂₋₆alkenyl-, —C₂₋₆alkynyl-,        —C₃₋₆cycloalkyl-, -phenyl-, -heteroaryl-, and -heterocyclic-;        wherein C₁₋₄alkyl, R^(a), R^(b), C₂₋₆alkenyl, C₂₋₆alkynyl,        C₃₋₆cycloalkyl, phenyl and heteroaryl may be optionally        substituted by one, two, three or more substituents selected        from the group consisting of C₁₋₄alkyl, C₁₋₄alkoxy,        —C(O)C₁₋₄alkyl, —C(O)—O—C₁₋₄alkyl, —C(O)—NR^(a)R^(b), halogen,        cyano, hydroxyl, cycloalkyl, heterocyclic, phenyl, heteroaryl,        R^(a) and R^(b), wherein the cycloalkyl, heterocyclic, phenyl,        or heteroaryl moiety is optionally substituted with one, two,        three or more substituents selected from halogen, amino, cyano,        hydroxyl, C₁₋₆alkyl, phenyl, heteroaryl, and amino;    -   W¹, independently for each occurrence, is selected from the        group consisting of a bond, —C₁₋₄alkylene-, —O—C₁₋₄alkylene-,        —C₁₋₄alkylene-C(O)—, —C(O)—C₁₋₄alkylene-,        —C₁₋₄alkylene-N(R^(a))—, —N(R^(a))—C₁₋₄alkylene-,        —C₁₋₄alkylene-O—C(O)—, —C(O)—O—C₁₋₄alkylene-, —NR^(a)—C(O)—,        —C₂₋₆alkenylene-, —C₂₋₆alkynylene-, —C₃₋₆cycloalkylene-,        -phenylene-, -heteroarylene-, and heterocyclene; wherein        C₁₋₄alkylene, C₂₋₆alkenylene, C₂₋₆alkynylene, C₃₋₆cycloalkylene,        R′, phenylene, heterocyclene, and heteroarylene are optionally        substituted independently, for each occurrence, with one, two,        three or more substituents selected from the group consisting of        C₁₋₄alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl,        —C(O)—O—C₁₋₄alkyl, cycloalkyl, heterocyclic, phenyl, heteroaryl,        halogen, hydroxyl, nitro sulfoxide, sulfone, sulfonamide and        cyano, wherein the cycloalkyl, heterocyclic, phenyl, or        heteroaryl moiety is optionally substituted with one, two, three        or more substituents selected from halogen, amino, cyano,        hydroxyl, C₁₋₆alkyl, phenyl, heteroaryl, and amino;    -   W², independently for each occurrence, is (a) absent; or (b)        selected from the group consisting of —C₁₋₄alkylene-,        —O—C₁₋₄alkylene-, —S—C₁₋₄alkylene, —C(O)—, —C(O)—C₁₋₄alkylene-,        —N(R′)—C₁₋₄alkylene-, —C(O)—O—C₁₋₄alkylene-, and        —C₂₋₆alkenylene-; wherein C₁₋₄alkylene and C₂₋₆alkenylene are        optionally substituted, independently for each occurrence, with        one, two, three, or more substituents selected from the group        consisting of C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl,        —C(O)—O—C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂, halogen, hydroxyl,        nitro, and cyano;    -   W³, independently for each occurrence, is selected from the        group consisting of —C₁₋₄alkylene-, —O—C₁₋₄alkylene-,        —S—C₁₋₄alkylene, —S(O)—, —C(O)—, —C(O)—C₁₋₄alkylene-,        —N(R′)—C₁₋₄alkylene-, —C(O)—O—C₁₋₄alkylene-, and        —C₂₋₆alkenylene-; wherein C₁₋₄alkylene and C₂₋₆alkenylene are        optionally substituted, independently for each occurrence, with        one, two, three, or more substituents selected from the group        consisting of C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl,        —C(O)—O—C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂, halogen, hydroxyl,        nitro, and cyano;    -   W⁵ is selected from the group consisting of —C₁₋₄alkylene-,        —C₁₋₄alkylene-N(R′)—, —C(O)C₁₋₄alkylene-, —C(O)—O—C₁₋₄alkylene-,        —C₂₋₆alkenylene-, —C₂₋₆alkynylene-, —C₃₋₆cycloalkylene-,        -heterocyclene-, -phenylene-, and heteroarylene; wherein        C₁₋₄alkylene, C₂₋₆alkenylene, C₂₋₆alkynylene, C₃₋₆cycloalkylene,        heterocyclene, phenylene, and heteroarylene are optionally        substituted by one, two, three or more substituents selected        from the group consisting of C₁₋₄alkyl, C₁₋₄alkoxy,        —C(O)C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂, halogen, hydroxyl, nitro,        and cyano;    -   wherein R^(W), W¹, W², W³, W⁵ and Y¹¹, Y²² and Y³³ may        optionally contain a catalytic moiety G selected from the group        consisting of -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, may optionally be substituted by one or        more substituents selected from the group consisting of halogen,        hydroxyl, cyano, C₁₋₆alkoxy, —COOH, —C(O)—NR^(a)R^(b),        —NR^(a)—C(O)—C₁₋₆alkyl, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H,        —SO₂—NR^(a)R^(b), —NR^(a)—SO₂— C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl;    -   Q³ is independently selected, for each occurrence, from the        group consisting of a bond, R^(W), —N(R′)—, —O—, —S—, and

-   -   BB, independently for each occurrence, is a 4-8 membered        cycloalkyl, heterocyclic, phenyl, naphthyl, or heteroaryl        moiety, wherein the cycloalkyl, heterocyclic, phenyl, naphthyl,        or heteroaryl moiety is optionally substituted with one, two,        three or more groups represented by R^(BB); wherein R¹,        independently for each occurrence, may be optionally bonded to        BB;    -   DD is a 4-8 membered heterocyclic ring, wherein the heterocyclic        ring is optionally substituted with one, two, three or more        groups represented by R^(BB);    -   each R^(BB) is independently selected, for each occurrence, from        the group consisting of hydrogen, halogen, nitro, cyano,        hydroxyl, amino, thio, oxo, —COOH, —CONHR′, substituted or        unsubstituted aliphatic, substituted or unsubstituted        heteroaliphatic, —C₁₋₄alkyl, —O—C₁₋₄alkyl, —N(R^(a))—C₁₋₄alkyl,        —C(O)C₁₋₄alkyl, —C(O)—NR^(a)R^(b), —C₂₋₆alkenyl, —C₂₋₆alkynyl,        —C₃₋₆cycloalkyl, heterocyclic, phenyl, phenoxy, heteroaryl,        —C₁₋₄alkylene-phenyl, —C₁₋₄alkylene-heteroaryl,        —C₁₋₄alkylene-heterocyclyl, —C₂₋₆alkenylene-phenyl,        —C₂₋₆alkenylene-heteroaryl, —C₂₋₆alkenylene-heterocyclyl,        —C₂₋₆alkynyl-phenyl, —C₂₋₆alkynyl-heteroaryl,        —C₂₋₆alkynyl-heterocyclyl; wherein C₁₋₄alkyl, C₂₋₆alkenyl,        C₂₋₆alkynyl, C₃₋₆cycloalkyl, phenyl, phenoxy, heterocyclyl, and        heteroaryl are optionally substituted by one, two, three or more        substituents selected from the group consisting of C₁₋₄alkyl,        C₁₋₄alkoxy, —C(O)C₁₋₄alkyl, —C(O)—NR^(a)R^(b), halogen, cyano,        hydroxyl, cycloalkyl, heterocyclic, phenyl, or heteroaryl; or        two R^(BB) together with the atoms to which they are attached        form a fused 5- or 6-membered cycloalkyl or heterocyclic        bicyclic ring system; and    -   R′ is independently selected, for each occurrence, from the        group consisting of hydrogen, substituted or unsubstituted        aliphatic, and substituted or unsubstituted heteroaliphatic.

In another embodiment, provided herein are drug conjugates representedby:L-Y¹-Q-Y²—Pand pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a moiety capable of binding to a cell surface receptor;    -   Y¹ and Y² are each independently a bond or spacer;    -   P is a payload moiety; and    -   Q is a siloxane comprising:        -   a first group selected from the group consisting of:

-   -   -    and        -   a second group selected from the group consisting of:

-   -   -    wherein the Si of the first group and the Si of the second            group are connected by an oxygen atom;        -   wherein:        -   R¹ and R² are selected independently for each occurrence            from the group consisting of L, H, P, —OH, C₁₋₆alkyl,            —O—C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl,            —C₁₋₆alkyl-NR^(a)R^(b), heterocyclyl, phenyl, naphthalene,            and heteroaryl; wherein C₁₋₆alkyl, C₂₋₆alkenyl,            C₃₋₆cycloalkyl, R^(a), R^(b), heterocyclyl, phenyl,            naphthalene, and heteroaryl, are optionally substituted by            one or more substituents selected from the group consisting            of halogen, cyano, hydroxyl, amino, C₁₋₆alkyl, heteroaryl,            and phenyl; or R¹ and R², together with the silicon to which            they are attached, may form a 4-8 membered heterocyclic            ring, optionally containing one or more additional            heteroatoms selected from O, S, or N; wherein the 4-8            membered heterocyclic ring is optionally substituted by one            or more substituents selected from the group consisting of            halogen, cyano, oxo, amino, and hydroxyl;        -   R^(a) and R^(b) are independently selected, for each            occurrence, from the group consisting of hydrogen,            C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl; wherein C₁₋₆alkyl,            C₂₋₆alkenyl, and phenyl may be optionally substituted by one            or more substituents selected from the group consisting of            halogen, cyano, oxo, and hydroxyl; or        -   R^(a) and R^(b), together with the nitrogen to which they            are attached, form a 4-7 membered heterocyclic ring,            optionally containing an additional heteroatom selected from            O, S, or N; wherein the 4-7 membered heterocyclic ring is            optionally substituted by one or more substituents selected            from the group consisting of halogen, cyano, oxo, amino, and            hydroxyl;        -   R^(W) is selected from the group consisting of a bond,            —C₁₋₄alkyl-, —O—C₁₋₄alkyl-, —N(R^(a))—C₁₋₄alkyl-,            —C₁₋₄alkyl-C(O)—, —C(O)C₁₋₄alkyl-, —C₁₋₄alkyl-O—C(O)—,            —C(O)—O—C₁₋₄alkyl-, —NR^(a)—C(O)—, —C₂₋₆alkenyl-,            —C₂₋₆alkynyl-, —C₃₋₆cycloalkyl-, -phenyl-, -heteroaryl-, and            -heterocyclic-; wherein C₁₋₄alkyl, R^(a), R^(b),            C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl, phenyl and            heteroaryl may be optionally substituted by one, two, three            or more substituents selected from the group consisting of            C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₄alkyl, —C(O)—O—C₁₋₄alkyl,            —C(O)—NR^(a)R^(b), halogen, cyano, hydroxyl, cycloalkyl,            heterocyclic, phenyl, heteroaryl, R^(a) and R^(b), wherein            the cycloalkyl, heterocyclic, phenyl, or heteroaryl moiety            is optionally substituted with one, two, three or more            substituents selected from halogen, amino, cyano, hydroxyl,            C₁₋₆alkyl, phenyl, heteroaryl, and amino;        -   W¹, independently for each occurrence, is selected from the            group consisting of a bond, —C₁₋₄alkylene-,            —O—C₁₋₄alkylene-, —C₁₋₄alkylene-C(O)—, —C(O)—C₁₋₄alkylene-,            —C₁₋₄alkylene-N(R^(a))—, —N(R^(a))—C₁₋₄alkylene-,            —C₁₋₄alkylene-O—C(O)—, —C(O)—O—C₁₋₄alkylene-, —NR^(a)—C(O)—,            —C₂₋₆alkenylene-, —C₂₋₆alkynylene-, —C₃₋₆cycloalkylene-,            -phenylene-, -heteroarylene-, and heterocyclene; wherein            C₁₋₄alkylene, C₂₋₆alkenylene, C₂₋₆alkynylene,            C₃₋₆cycloalkylene, R′, phenylene, heterocyclene, and            heteroarylene are optionally substituted independently, for            each occurrence, with one, two, three or more substituents            selected from the group consisting of C₁₋₄alkyl,            C₂₋₆alkenyl, C₂₋₆alkynyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl,            —C(O)—O—C₁₋₄alkyl, cycloalkyl, heterocyclic, phenyl,            heteroaryl, halogen, hydroxyl, nitro sulfoxide, sulfone,            sulfonamide and cyano, wherein the cycloalkyl, heterocyclic,            phenyl, or heteroaryl moiety is optionally substituted with            one, two, three or more substituents selected from halogen,            amino, cyano, hydroxyl, C₁₋₆alkyl, phenyl, heteroaryl, and            amino;        -   W², independently for each occurrence, is (a) absent; or (b)            selected from the group consisting of —C₁₋₄alkylene-,            —O—C₁₋₄alkylene-, —S—C₁₋₄alkylene, —C(O)—,            —C(O)—C₁₋₄alkylene-, —N(R′)—C₁₋₄alkylene-,            —C(O)—O—C₁₋₄alkylene-, and —C₂₋₆alkenylene-; wherein            C₁₋₄alkylene and C₂₋₆alkenylene are optionally substituted,            independently for each occurrence, with one, two, three, or            more substituents selected from the group consisting of            C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl, —C(O)—O—C₁₋₄alkyl,            —C(O)—N(R′)₂, —N(R′)₂, halogen, hydroxyl, nitro, and cyano;        -   W³, independently for each occurrence, is selected from the            group consisting of —C₁₋₄alkylene-, —O—C₁₋₄alkylene-,            —S—C₁₋₄alkylene, —S(O)—, —C(O)—, —C(O)—C₁₋₄alkylene-,            —N(R′)—C₁₋₄alkylene-, —C(O)—O—C₁₋₄alkylene-, and            —C₂₋₆alkenylene-; wherein C₁₋₄alkylene and C₂₋₆alkenylene            are optionally substituted, independently for each            occurrence, with one, two, three, or more substituents            selected from the group consisting of C₁₋₄alkyl, C₁₋₄alkoxy,            —C(O)C₁₋₆alkyl, —C(O)—O—C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂,            halogen, hydroxyl, nitro, and cyano;        -   W⁵ is selected from the group consisting of —C₁₋₄alkylene-,            —C₁₋₄alkylene-N(R′)—, —C(O)C₁₋₄alkylene-,            —C(O)—O—C₁₋₄alkylene-, —C₂₋₆alkenylene-, —C₂₋₆alkynylene-,            —C₃₋₆cycloalkylene-, -heterocyclene-, -phenylene-, and            heteroarylene; wherein C₁₋₄alkylene, C₂₋₆alkenylene,            C₂₋₆alkynylene, C₃₋₆cycloalkylene, heterocyclene, phenylene,            and heteroarylene are optionally substituted by one, two,            three or more substituents selected from the group            consisting of C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₄alkyl,            —C(O)—O—C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂, halogen, hydroxyl,            nitro, and cyano;        -   wherein R^(W), W¹, W², W³, W⁵Y¹ and Y² may optionally            contain a catalytic moiety G selected from the group            consisting of -heteroaryl-, —O-heteroaryl-,            —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0,            1, or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,            -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-            (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,            —SO₂—NR^(a)-phenyl-, —C(O)—C₀₋₆alkyl, —C(O)—O—C₀₋₆alkyl-,            —O—C(O)—C₀₋₆alkyl-, —NR^(a)—C(O)—C₀₋₆alkyl-,            —C(O)—NR^(a)—C₀₋₆alkyl-, and —NR^(a)—C₀₋₆alkyl-; wherein            -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,            —S(O)_(w)-heteroaryl-(wherein w is 0, 1, or 2),            —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,            —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is            0, 1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may            optionally be substituted by one or more substituents            selected from the group consisting of halogen, hydroxyl,            cyano, C₁₋₆alkyl, C₁₋₆alkoxy, —COOH, —C(O)—O—C₁₋₆alkyl,            —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,            —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),            —NR^(a)—SO₂—C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆ alkyl;        -   Q³ is independently selected, for each occurrence, from the            group consisting of a bond, R^(W), —N(R′)—, —O—, —S—, and

-   -   -   R′ is independently selected, for each occurrence, from the            group consisting of hydrogen, substituted or unsubstituted            aliphatic, and substituted or unsubstituted heteroaliphatic;        -   BB, independently for each occurrence, is a 4-8 membered            cycloalkyl, heterocyclic, phenyl, naphthyl, or heteroaryl            moiety, wherein the cycloalkyl, heterocyclic, phenyl,            naphthyl, or heteroaryl moiety is optionally substituted            with one, two, three or more groups represented by R^(BB);            wherein R¹, independently for each occurrence, may be            optionally bonded to BB; and        -   DD is a 4-8 membered heterocyclic ring, wherein the            heterocyclic ring is optionally substituted with one, two,            three or more groups represented by R^(BB);        -   each R^(BB) is independently selected, for each occurrence,            from the group consisting of hydrogen, halogen, nitro,            cyano, hydroxyl, amino, thio, oxo, —COOH, —CONHR′,            substituted or unsubstituted aliphatic, substituted or            unsubstituted heteroaliphatic, —C₁₋₄alkyl, —O—C₁₋₄alkyl,            —N(R^(a))—C₁₋₄ alkyl, —C(O)C₁₋₄ alkyl, —C(O)—O—C₁₋₄alkyl,            —C(O)—NR^(a)R^(b), —C₂₋₆alkenyl, —C₂₋₆alkynyl,            —C₃₋₆cycloalkyl, heterocyclic, phenyl, phenoxy, heteroaryl,            —C₁₋₄alkylene-phenyl, —C₁₋₄alkylene-heteroaryl,            —C₁₋₄alkylene-heterocyclyl, —C₂₋₆alkenylene-phenyl,            —C₂₋₆alkenylene-heteroaryl, —C₂₋₆alkenylene-heterocyclyl,            —C₂₋₆alkynyl-phenyl, —C₂₋₆alkynyl-heteroaryl,            —C₂₋₆alkynyl-heterocyclyl; wherein C₁₋₄alkyl, C₂₋₆alkenyl,            C₂₋₆alkynyl, C₃₋₆cycloalkyl, phenyl, phenoxy, heterocyclyl,            and heteroaryl are optionally substituted by one, two, three            or more substituents selected from the group consisting of            C₁ alkyl, C₁₋₄alkoxy, —C(O)C₁₋₄alkyl, —C(O)—O—C₁₋₄alkyl,            —C(O)—NR^(a)R^(b), halogen, cyano, hydroxyl, cycloalkyl,            heterocyclic, phenyl, or heteroaryl; or two R^(BB) together            with the atoms to which they are attached form a fused 5- or            6-membered cycloalkyl or heterocyclic bicyclic ring system.

Provided herein, in an embodiment, are drug conjugates represented by:

and pharmaceutically acceptable salts, cocrystals, stereoisomers,metabolites, tautomers, solvates, and hydrates thereof, wherein:

-   -   L is a moiety capable of binding to a cell surface receptor;    -   Y¹ and Y² are each independently a bond or spacer;    -   P is a payload moiety;    -   R¹ and R² are selected independently for each occurrence from        the group consisting of L, P, H, —OH, C₁₋₆alkyl, —O—C₁₋₆ alkyl,        C₂₋₆alkenyl, C₃₋₆cycloalkyl, —C₁₋₆ alkyl-NR^(a)R_(b),        heterocyclyl, phenyl, naphthalene, and heteroaryl; wherein        C₁₋₆alkyl, C₂₋₆alkenyl, C₃₋₆cycloalkyl, R^(a), R^(b),        heterocyclyl, phenyl, naphthalene, and heteroaryl, are        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, hydroxyl, amino,        C₁₋₆alkyl, heteroaryl, and phenyl; or R¹ and R², together with        the silicon to which they are attached, may form a 4-8 membered        heterocyclic ring, optionally containing one or more additional        heteroatoms selected from O, S, or N; wherein the 4-8 membered        heterocyclic ring is optionally substituted by one or more        substituents selected from the group consisting of halogen,        cyano, oxo, amino, and hydroxyl;    -   R^(a) and R^(b) are independently selected, for each occurrence,        from the group consisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl,        and phenyl; wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be        optionally substituted by one or more substituents selected from        the group consisting of halogen, cyano, oxo, and hydroxyl; or    -   R^(a) and R^(b), together with the nitrogen to which they are        attached, form a 4-7 membered heterocyclic ring, optionally        containing an additional heteroatom selected from O, S, or N;        wherein the 4-7 membered heterocyclic ring is optionally        substituted by one or more substituents selected from the group        consisting of halogen, cyano, oxo, amino, and hydroxyl;    -   R^(W) is selected from the group consisting of a bond,        —C₁₋₄alkyl-, —O—C₁₋₄alkyl-, —C₁₋₄alkyl-C(O)—, —C(O)C₁₋₄alkyl-,        —C₁₋₄alkyl-O—C(O)—, —C(O)—O—C₁₋₄alkyl-, —NR^(a)—C(O)—,        —C₂₋₆alkenyl-, —C₂₋₆alkynyl-, —C₃₋₆cycloalkyl-, -phenyl-,        -heteroaryl-, and -heterocyclic-; wherein C₁₋₄alkyl, R^(a),        R^(b), C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl, phenyl and        heteroaryl may be optionally substituted by one, two, three or        more substituents selected from the group consisting of        C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₄alkyl, —C(O)—O—C₁₋₄alkyl,        —C(O)—NR^(a)R^(b), halogen, cyano, hydroxyl, cycloalkyl,        heterocyclic, phenyl, heteroaryl, R^(a) and R^(b), wherein the        cycloalkyl, heterocyclic, phenyl, or heteroaryl moiety is        optionally substituted with one, two, three or more substituents        selected from halogen, amino, cyano, hydroxyl, C₁₋₆alkyl,        phenyl, heteroaryl, and amino;    -   W¹, independently for each occurrence, is selected from the        group consisting of a bond, —C₁₋₄alkylene-, —O—C₁₋₄alkylene-,        —C₁₋₄alkylene-C(O)—, —C(O)—C₁₋₄alkylene-,        —C₁₋₄alkylene-N(R^(a))—, —N(R^(a))—C₁₋₄alkylene-,        —C₁₋₄alkylene-O—C(O)—, —C(O)—O—C₁₋₄alkylene-, —NR^(a)—C(O)—,        —C₂₋₆alkenylene-, —C₂₋₆alkynylene-, —C₃₋₆cycloalkylene-,        -phenylene-, -heteroarylene-, and heterocyclene; wherein        C₁₋₄alkylene, C₂₋₆alkenylene, C₂₋₆alkynylene, C₃₋₆cycloalkylene,        R′, phenylene, heterocyclene, and heteroarylene are optionally        substituted independently, for each occurrence, with one, two,        three or more substituents selected from the group consisting of        C₁₋₄alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl,        —C(O)—O—C₁alkyl, cycloalkyl, heterocyclic, phenyl, heteroaryl,        halogen, hydroxyl, nitro sulfoxide, sulfone, sulfonamide and        cyano, wherein the cycloalkyl, heterocyclic, phenyl, or        heteroaryl moiety is optionally substituted with one, two, three        or more substituents selected from halogen, amino, cyano,        hydroxyl, C₁₋₆alkyl, phenyl, heteroaryl, and amino;    -   W², independently for each occurrence, is (a) absent; or (b)        selected from the group consisting of —C₁₋₄alkylene-,        —O—C₁₋₄alkylene-, —S—C₁₋₄alkylene, —C(O)—, —C(O)—C₁₋₄alkylene-,        —N(R′)—C₁₋₄alkylene-, —C(O)—O—C₁₋₄alkylene-, and        —C₂₋₆alkenylene-; wherein C₁₋₄alkylene and C₂₋₆alkenylene are        optionally substituted, independently for each occurrence, with        one, two, three, or more substituents selected from the group        consisting of C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl,        —C(O)—O—C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂, halogen, hydroxyl,        nitro, and cyano;    -   W³, independently for each occurrence, is selected from the        group consisting of —C₁₋₄alkylene-, —O—C₁₋₄alkylene-,        —S—C₁₋₄alkylene, —S(O)—, —C(O)—, —C(O)—C₁₋₄alkylene-,        —N(R′)—C₁₋₄alkylene-, —C(O)—O—C₁₋₄alkylene-, and        —C₂₋₆alkenylene-; wherein C₁₋₄alkylene and C₂₋₆alkenylene are        optionally substituted, independently for each occurrence, with        one, two, three, or more substituents selected from the group        consisting of C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₆alkyl,        —C(O)—O—C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂, halogen, hydroxyl,        nitro, and cyano;    -   W⁵ is selected from the group consisting of —C₁₋₄alkylene-,        —C₁₋₄alkylene-N(R′)—, —C(O)C₁₋₄alkylene-, —C(O)—O—C₁₋₄alkylene-,        —C₂₋₆alkenylene-, —C₂₋₆alkynylene-, —C₃₋₆cycloalkylene-,        -heterocyclene-, -phenylene-, and heteroarylene; wherein        C₁₋₄alkylene, C₂₋₆alkenylene, C₂₋₆alkynylene, C₃₋₆cycloalkylene,        heterocyclene, phenylene, and heteroarylene are optionally        substituted by one, two, three or more substituents selected        from the group consisting of C₁₋₄alkyl, C₁₋₄alkoxy,        —C(O)C₁₋₄alkyl, —C(O)—O—C₁₋₄alkyl, —C(O)—N(R′)₂, —N(R′)₂,        halogen, hydroxyl, nitro, and cyano;    -   wherein R^(W), W¹, W², W³, W⁵ and Y²² may optionally contain a        catalytic moiety G selected from the group consisting of        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, may optionally be substituted by one or        more substituents selected from the group consisting of halogen,        hydroxyl, cyano, C₁₋₆alkyl, C₁₋₆alkoxy, —COOH,        —C(O)—O—C₁₋₆alkyl, —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂—C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl;    -   Q³ is independently selected, for each occurrence, from the        group consisting of a bond, R^(W), —N(R′)—, —O—, —S—, and

-   -   R′ is independently selected, for each occurrence, from the        group consisting of hydrogen, substituted or unsubstituted        aliphatic, and substituted or unsubstituted heteroaliphatic;    -   BB, independently for each occurrence, is a 4-8 membered        cycloalkyl, heterocyclic, phenyl, naphthyl, or heteroaryl        moiety, wherein the cycloalkyl, heterocyclic, phenyl, naphthyl,        or heteroaryl moiety is optionally substituted with one, two,        three or more groups represented by R^(BB); wherein R¹,        independently for each occurrence, may be optionally bonded to        BB; and    -   DD is a 4-8 membered heterocyclic ring, wherein the heterocyclic        ring is optionally substituted with one, two, three or more        groups represented by R^(BB);    -   each R^(BB) is independently selected, for each occurrence, from        the group consisting of hydrogen, halogen, nitro, cyano,        hydroxyl, amino, thio, oxo, —COOH, —CONHR′, substituted or        unsubstituted aliphatic, substituted or unsubstituted        heteroaliphatic, —C₁₋₄alkyl, —O—C₁₋₄alkyl, —N(R^(a))—C₁₋₄alkyl,        —C(O)C₁₋₄alkyl, —C(O)—O—C₁₋₄alkyl, —C(O)—NR^(a)R^(b),        —C₂₋₆alkenyl, —C₂₋₆alkynyl, —C₃₋₆cycloalkyl, heterocyclic,        phenyl, phenoxy, heteroaryl, —C₁₋₄alkylene-phenyl,        —C₁₋₄alkylene-heteroaryl, —C₁₋₄alkylene-heterocyclyl,        —C₂₋₆alkenylene-phenyl, —C₂₋₆alkenylene-heteroaryl,        —C₂₋₆alkenylene-heterocyclyl, —C₂₋₆alkynyl-phenyl,        —C₂₋₆alkynyl-heteroaryl, —C₂₋₆alkynyl-heterocyclyl; wherein        C₁₋₄alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl, C₃₋₆cycloalkyl, phenyl,        phenoxy, heterocyclyl, and heteroaryl are optionally substituted        by one, two, three or more substituents selected from the group        consisting of C₁₋₄alkyl, C₁₋₄alkoxy, —C(O)C₁₋₄alkyl,        —C(O)—O—C₁₋₄alkyl, —C(O)—NR^(a)R^(b), halogen, cyano, hydroxyl,        cycloalkyl, heterocyclic, phenyl, or heteroaryl; or two R^(BB)        together with the atoms to which they are attached form a fused        5- or 6-membered cycloalkyl or heterocyclic bicyclic ring        system.        Scaffold Based Conjugates

In another embodiment, a pharmaceutically acceptable drug deliveryconjugate is provided, comprising a scaffold having a plurality ofcovalently bonded moieties each selected from the group consisting of:—Si(Y_(y)—X)₂—O—Si—(Y_(y)—X)₃  (AA);—Si(Y_(y)—X)_(t)—(O—Y_(y)—X)_(q)  (BB);—O—Si(Y_(y)—X)_(t)—(O—Y_(y)—X)_(q)  (CC); and—O—Si(Y_(y)—X)_(q)  (DD);

-   -   wherein    -   y, for each occurrence of Y, is 0 or 1;    -   q, for each occurrence, is 0, 1, 2, or 3;    -   t is (3-q);    -   Y is a divalent spacer moiety; wherein Y may optionally contain        a catalytic moiety G selected from the group consisting of        -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-(wherein        w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may        optionally be substituted by one or more substituents selected        from the group consisting of halogen, hydroxyl, cyano,        C₁₋₆alkoxy, —COOH, —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,        —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b),        —NR^(a)—SO₂—C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl;    -   X is independently selected for each occurrence from P, a        payload moiety or payload cassette; L, a targeting moiety, and        R, such that at least one P and one L is present; and    -   R, for each occurrence, may the same or different and is a        non-interfering moiety. A scaffold may be any system that        provides multiple attachments to each Si moiety (AA), (BB), (CC)        or (DD), can be selected for example, from a ring system, a        polymer, a dendrimer, a protein, a nanoparticle, and viral        capsid. Such a multi targeting-moiety/payload conjugate may        facilitate e.g., more than one therapeutic to a patient and/or        cellular or molecular target. In some embodiments, one or more        of the covalently bound Si moieties and/or payload moieties is        cleavable, e.g., acid- or base-cleavable, and/or the conjugate        is substantially stable in aqueous solution having a pH of        between 7 and 7.5 and/or hydrolytically cleaves in aqueous        solution having a pH less than 7 or greater than 7.5 to release        one or more of the payload moieties.        Antibody-Drug Conjugates

In an embodiment, a pharmaceutically acceptable drug conjugate isprovided, comprising: a biological sequence selected from the groupconsisting of an antibody, antibody fragment, protein, or polypeptide,at least one therapeutic agent covalently attached to the biologicalsequence by a connector containing a cleavable Si-heteroatom moiety(e.g., a siloxane or silylether moiety). In some embodiments, the drugconjugate is substantially stable in aqueous solution having a pHbetween 7 and 7.5 and/or hydrolytically cleaves in aqueous solutionhaving a pH less than 7 or greater than 7.5 at 25° C. or 37° C. torelease the therapeutic agent. For instance, in some embodiments, anaqueous solution having a pH of between about 7 and about 7.5 may beselected from the group consisting of serum, plasma, whole blood, or acytosol. In certain embodiments, an aqueous solution having a pH lessthan about 7 or greater than about 7.5 may be selected from the groupconsisting of bile fluids, an endosome, a lysosome, or a tumor orinflammatory microenvironment.

For example, a drug conjugate provided that includes an antibody (e.g.,a monoclonal antibody), covalently bonded through a natural or unnaturalamino acid to a silylether or siloxane moiety; an optional divalentspacer moiety covalently bound to one or more of a silylether orsiloxane moiety; and one or more payload moieties covalently bound to adivalent spacer moiety or to a silylether or siloxane moiety.

For example, provided herein is an antibody drug conjugate representedby:

-   -   antibody-[spacer]-([Si-moiety]-[spacer]-payload)_(n), wherein    -   n is 1, 2, or more; and    -   [Si moiety] is selected from a silylether or siloxane moiety,        and is covalently bound to the antibody for each occurrence        directly or indirectly from an oxygen or silicon atom on the Si        moiety to natural or unnatural amino acid present on the        antibody;    -   where one or more [spacer] moieties, for each occurrence, may be        present or absent. For example, the antibody or antibody        fragment may have an amino acid sequence containing one or two        non-naturally occurring amino acids. In some embodiments an        acid- or base-cleavable connector or spacer is attached to the        antibody using a bioorthogonal moiety.

For example, provided here in is a drug -antibody conjugate, representedby:Antibody-[Sn(Y_(y)—X)₂—O—Si—(Y_(y)—X)₃]_(n);Antibody-[Sn(Y_(y)—X)_(t)—(O—Y_(y)—X)_(q)]_(n);Antibody-[O—Si(Y_(y)—X)_(t)—(O—Y_(y)—X)_(q)]_(n) orAntibody-[—O—Si(Y_(y)—X)_(q)]_(n);

-   -   wherein    -   y, for each occurrence of Y, is 0 or 1;    -   q, for each occurrence, is 0, 1, 2, or 3;    -   t is (3-q);    -   n is 1, 2, or more;    -   Y is the divalent spacer moiety; wherein Y may optionally        contain a catalytic moiety G selected from the group consisting        of a bond, -heteroaryl-, —O-heteroaryl-, —NR^(a)-heteroaryl-,        —S(O)_(w)-heteroaryl- (wherein w is 0, 1, or 2),        —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,        —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0,        1, or 2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-,        —C(O)—C₀₋₆alkyl-, —C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-,        —NR^(a)—C(O)—C₀₋₆alkyl-, —C(O)—NR^(a)—C₀₋₆alkyl-, and        —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-, —O-heteroaryl-,        —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is 0, 1,        or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-,        -phenyl-, —O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl-        (wherein w is 0, 1, or 2), —NR^(a)—SO₂-phenyl-,        —SO₂—NR^(a)-phenyl-, may optionally be substituted by one or        more substituents selected from the group consisting of halogen,        hydroxyl, cyano, C₁₋₆alkoxy, —COOH, —C(O)—NR^(a)R^(b),        —NR^(a)—C(O)—C₁₋₆alkyl, —C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H,        —SO₂—NR^(a)R^(b), —NR^(a)—SO₂— C₁₋₆alkyl, and        —SO₂—NR^(a)—C₁₋₆alkyl;    -   X is independently selected for each occurrence from P, a        payload moiety; L, a targeting moiety, and R, such that at least        one P is present; and    -   R, for each occurrence, may the same or different and is a        non-interfering moiety.

FIG. 12 shows an exemplary and pictorial heterogeneous or homogeneoussiloxane mAb-drug conjugate. For example, the siloxane or silylethermoiety can be either incorporated via unnatural silanolic-amino acidsengineered into the mAb, or attached to naturally occurring amino acidssuch as lysine, cysteine, or threonine via appropriate linkerchemistries (amides, disulfides, esters). Exemplary engineeredincorporation of silanol amino acids are exemplified here in anembodiment with n=2 attachments. In some embodiments, a contemplatedmAb-drug conjugate will have substantially identical/reproduciblenumbers of payloads per mAb.

FIG. 13 shows an exemplary and pictorial heterogeneous or homogeneoussilyl ether mAb-drug conjugate embodiment. For example, the silylethermoiety can be attached to naturally occurring amino acids such asthreonine and tyrosine using appropriate chemistries or the silylethermoiety can be either incorporated via unnatural silanolic-amino acidsengineered into the mAb, or, properly substituted silanols (e.g.Ar—SiR3, R4OH) attached to naturally occurring amino acids such aslysine, cysteine, threonine via appropriate linker chemistries (amides,disulfides, esters).

FIG. 14 pictorially indicates a disclosed embodiment and route tohomogeneous silicon mAb-drug conjugates. For example, unnatural aminoacids bearing irreversible bioorthogonal moieties may be used; once theprotein is synthesized, a silanol may be incorporated viableirreversible coupling to the bioorthogonal moiety.

Therapeutic Payloads

In various embodiments, the payload may be a therapeutic moiety. Thetherapeutic moiety can be, for example, a cytotoxic moiety. A cytotoxicmoiety can be analogs of SN-38, bendamustine, a VDA, doxorubicin,pemetrexed, vorinostat, lenalidomide, irinotecan, ganetespib, docetaxel,17-AAG, 5-FU, abiraterone, crizotinib, KW-2189, BUMB2, DC1, CC-1065,adozelesin, or (a) fragment(s) thereof.

In various embodiments, the payload may be selected from an antifolateor fragments thereof (e.g., temozolomide, mitozolomide, nitrogenmustards, estramustine, or chloromethine).

In various embodiments, the payload may be selected from:peptidyl-prolyl isomerase ligands, e.g., FK506 (tacrolimus); rapamycin,cyclosporin A; steroid hormone receptor ligands, e.g., naturallyoccurring steroid hormones, such as estrogen, progestin, testosterone,as well as synthetic derivatives and mimetics thereof; small moleculesthat bind to cytoskeletal proteins, e.g., antimitotic agents, such astaxanes, colchicine, colcemid, nocadozole, vinblastine, and vincristine,actin binding agents, such as cytochalasin, latrunculin, halloidin;lenalidomide, pomalidomide, camptothecins including SN-38, topotecan,combretastatins, capecitabine, gemcitabine, vinca alkaloids,platinum-containing compounds, metformin, HDAC inhibitors (e.g.,suberoylanilidehydroxamic acid (SAHA)), thymidylate synthase inhibitorssuch as methotrexate, pemetrexed, and raltitrexed; nitrogen mustardssuch as bendamustine and melphalan; 5-fluorouracil (5-FU) and itsderivatives; and agents used in ADC drugs, such as vedotin and DM1.

In various embodiments, the payload may be selected from: centralnervous system depressants, e.g., general anesthetics (barbiturates,benzodiazepines, steroids, cyclohexanone derivatives, and miscellaneousagents), sedative-hypnotics (benzodiazepines, barbiturates,piperidinediones and triones, quinazoline derivatives, carbamates,aldehydes and derivatives, amides, acyclic ureides, benzazepines andrelated drugs, phenothiazines), central voluntary muscle tone modifyingdrugs (anticonvulsants, such as hydantoins, barbiturates,oxazolidinediones, succinimides, acylureides, glutarimides,benzodiazepines, secondary and tertiary alcohols, dibenzazepinederivatives, valproic acid and derivatives, GABA analogs), analgesics(morphine and derivatives, oripavine derivatives, morphinan derivatives,phenylpiperidines, 2,6-methane-3-benzazocaine derivatives,diphenylpropylamines and isosteres, salicylates, 7-aminophenolderivatives, 5-pyrazolone derivatives, arylacetic acid derivatives,fenamates and isosteres) and antiemetics (anticholinergics,antihistamines, antidopaminergics); central nervous system stimulants,e.g., analeptics (respiratory stimulants, convulsant stimulants,psychomotor stimulants), narcotic antagonists (morphine derivatives,oripavine derivatives, 2,6-methane-3-benzoxacine derivatives, morphinanderivatives) nootropics; psychopharmacological/psychotropics, e.g.,anxiolytic sedatives (benzodiazepines, propanediol carbamates)antipsychotics (phenothiazine derivatives, thioxanthine derivatives,other tricyclic compounds, butyrophenone derivatives and isosteres,diphenylbutylamine derivatives, substituted benzamides, arylpiperazinederivatives, indole derivatives), antidepressants (tricyclic compounds,MAO inhibitors).

In various embodiments, the payload may be selected from: respiratorytract drugs, e.g., central antitussives (opium alkaloids and theirderivatives); immunosuppressive agents; pharmacodynamic agents, such asperipheral nervous system drugs, e.g., local anesthetics (esterderivatives, amide derivatives); drugs acting at synaptic orneuroeffector junctional sites, e.g., cholinergic agents, cholinergicblocking agents, neuromuscular blocking agents, adrenergic agents,antiadrenergic agents; smooth muscle active drugs, e.g., spasmolytics(anticholinergics, musculotropic spasmolytics), vasodilators, smoothmuscle stimulants; histamines and antihistamines, e.g., histamine andderivative thereof (betazole), antihistamines (Hi-antagonists,H2-antagonists), histamine metabolism drugs; cardiovascular drugs, e.g.,cardiotonics (plant extracts, butenolides, pentadienolids, alkaloidsfrom erythrophleum species, ionophores, -adrenoceptor stimulants),antiarrhythmic drugs, antihypertensive agents, antilipidemic agents(clofibric acid derivatives, nicotinic acid derivatives, hormones andanalogs, antibiotics, salicylic acid and derivatives), antivaricosedrugs, hemo styptics; chemo therapeutic agents, such as anti-infectiveagents, e.g., ectoparasiticides (chlorinated hydrocarbons, pyrethins,sulfurated compounds), anthelmintics, antiprotozoal agents, antimalarialagents, antiamebic agents, antileiscmanial drugs, antitrichomonalagents, antitrypanosomal agents, sulfonamides, antimycobacterial drugs,antiviral chemotherapeutics, and cytostatics, i.e., antineoplasticagents or cytotoxic drugs, such as alkylating agents, e.g.,mechlorethamine hydrochloride (nitrogen mustard, mustargen, HN2),cyclophosphamide (Cytovan, Endoxana), ifosfamide (IFEX), chlorambucil(Leukeran), Melphalan (phenylalanine mustard, L-sarcolysin, Alkeran,L-PAM), busulfan (Myleran), Thiotepa (triethylenethiophosphoramide),carmustine (BiCNU, BCNU), lomustine (CeeNU, CCNU), streptozocin(Zanosar); plant alkaloids, e.g., vincristine (Oncovin), vinblastine(Velban, Velbe), paclitaxel (Taxol); antimetabolites, e.g., methotrexate(MTX), mercaptopurine (Purinethol, 6-MP), thioguanine (6-TG),fluorouracil (5-FU), cytarabine (Cytosar-U, Ara-C), azacitidine(Mylosar, 5-AZA); antibiotics, e.g., dactinomycin (Actinomycin D,Cosmegen), doxorubicin (Adriamycin), daunorubicin (duanomycin,Cerubidine), idarubicin (Idamycin), bleomycin (Blenoxane), picamycin(Mithramycin, Mithracin), mitomycin (Mutamycin), and other anticellularproliferative agents, e.g., hydroxyurea (Hydrea), procarbazine(Mutalane), dacarbazine (DTIC-Dome), cisplatin (Platinol) carboplatin(Paraplatin), asparaginase (Elspar), etoposide (VePesid, VP-16-213),amsarcrine (AMSA, m-AMSA), mitotane (Lysodren), or mitoxantrone(Novatrone).

In various embodiments, the payload may be selected from:anti-inflammatory agents; antibiotics, such as: aminoglycosides, e.g.,amikacin, apramycin, arbekacin, bambermycins, butirosin, dibekacin,dihydrostreptomycin, fortimicin, gentamicin, isepamicin, kanamycin,micronomcin, neomycin, netilmicin, paromycin, ribostamycin, sisomicin,spectinomycin, streptomycin, tobramycin, trospectomycin; amphenicols,e.g., azidamfenicol, chloramphenicol, florfenicol, and theimaphenicol;ansamycins, e.g., rifamide, rifampin, rifamycin, rifapentine, rifaximin;β-lactams, e.g., carbacephems, carbapenems, cephalosporins, cehpamycins,monobactams, oxaphems, penicillins; lincosamides, e.g., clinamycin,lincomycin; macrolides, e.g., clarithromycin, dirthromycin,erythromycin; polypeptides, e.g., amphomycin, bacitracin, capreomycin;tetracyclines, e.g., apicycline, chlortetracycline, clomocycline;synthetic antibacterial agents, such as 2,4-diaminopyrimidines,nitrofurans, quinolones and analogs thereof, sulfonamides, or sulfones.

In various embodiments, the payload may be selected from: antifungalagents, such as: polyenes, e.g., amphotericin B, candicidin,dermostatin, filipin, fungichromin, hachimycin, hamycin, lucensomycin,mepartricin, natamycin, nystatin, pecilocin, perimycin; syntheticantifungals, such as allylamines, e.g., butenafine, naftifine,terbinafine; imidazoles, e.g., bifonazole, butoconazole, chlordantoin,chlormidazole, thiocarbamates, e.g., tolciclate, triazoles, e.g.,fluconazole, itraconazole, or terconazole.

In various embodiments, the payload may be selected from: anthelmintics,such as: arecoline, aspidin, aspidinol, dichlorophene, embelin, kosin,napthalene, niclosamide, pelletierine, quinacrine, alantolactone,amocarzine, amoscanate, ascaridole, bephenium, bitoscanate, carbontetrachloride, carvacrol, cyclobendazole, or diethylcarbamazine.

In various embodiments, the payload may be selected from: antimalarials,such as: acedapsone, amodiaquin, arteether, artemether, artemisinin,artesunate, atovaquone, bebeerine, berberine, chirata, chlorguanide,chloroquine, chlorprogaunil, cinchona, cinchonidine, cinchonine,cycloguanil, gentiopicrin, halofantrine, hydroxychloroquine, mefloquinehydrochloride, 3-methylarsacetin, pamaquine, plasmocid, primaquine,pyrimethamine, quinacrine, quinidine, quinine, quinocide, quinoline, ordibasic sodium arsenate.

In various embodiments, the payload may be selected from: antiprotozoanagents, such as: acranil, tinidazole, ipronidazole, ethylstibamine,pentamidine, acetarsone, aminitrozole, anisomycin, nifuratel,tinidazole, benzidazole, or suramin.

In various embodiments, the payload may be selected from: docetaxel orpaclitaxel; BEZ235; temsirolimus; PLX4032; cisplatin; AZD8055; andcrizotinib.

In various embodiments, the payload may be a topotecan or irinotecan.

In various embodiments the payload may be selected from siRNA, mRNA ormiRNA optionally in combination with endosomal escape enhancers.

In various embodiments the payload may be selected from antigens.

Methods

In some embodiments, contemplated conjugates may be administered to apatient in need thereof a therapeutically effective amount of the one ormore payloads. In some embodiments, a payload moiety may have amolecular weight between 50 Da and 2000 Da, in some embodiments between50 Da and 1500 Da, in some embodiments, between 50 Da and 1000 Da, andin some embodiments, between 50 Da and 500 Da. In certain embodiments, atargeting moiety may have a molecular weight of less than 2000 Da, insome embodiments, less than 1000 Da, and in some embodiments less than500 Da.

Disclosed conjugates may be administered to patients (animals andhumans) in need of such treatment in dosages that will provide optimalpharmaceutical efficacy. It will be appreciated that the dose requiredfor use in any particular application will vary from patient to patient,not only with the particular compound or composition selected, but alsowith the route of administration, the nature of the condition beingtreated, the age and condition of the patient, concurrent medication orspecial diets then being followed by the patient, and other factorswhich those skilled in the art will recognize, with the appropriatedosage ultimately being at the discretion of the attendant physician.For treating clinical conditions and diseases noted above, a compoundmay be administered orally, subcutaneously, topically, parenterally, byinhalation spray or rectally in dosage unit formulations containingconventional non-toxic pharmaceutically acceptable carriers, adjuvants,and vehicles. Parenteral administration may include subcutaneousinjections, intravenous or intramuscular injections, or infusiontechniques.

Treatment can be continued for as long or as short a period as desired.The compositions may be administered on a regimen of, for example, oneto four or more times per day. A suitable treatment period can be, forexample, at least about one week, at least about two weeks, at leastabout one month, at least about six months, at least about 1 year, orindefinitely. A treatment period can terminate when a desired result,for example a partial or total alleviation of symptoms, is achieved.

In another aspect, conjugates disclosed here may be formulated togetherwith a pharmaceutically acceptable carrier provided. In particular, thepresent disclosure provides conjugates disclosed herein formulatedtogether with one or more pharmaceutically acceptable carriers. Theseformulations include those suitable for oral, rectal, topical, buccal,parenteral (e.g., subcutaneous, intramuscular, intradermal, orintravenous), rectal, vaginal, or aerosol administration, although themost suitable form of administration in any given case will depend onthe degree and severity of the condition being treated and on the natureof the particular compound being used. For example, disclosedcompositions may be formulated as a unit dose, and/or may be formulatedfor oral, i.v., or subcutaneous administration.

Exemplary pharmaceutical compositions may be used in the form of apharmaceutical preparation, for example, in solid, semisolid,spray-dried, dispersion, or liquid form, which contains one or more ofthe compounds, as an active ingredient, in admixture with an organic orinorganic carrier or excipient suitable for external, enteral, orparenteral applications. The active ingredient may be compounded, forexample, with the usual non-toxic, pharmaceutically acceptable carriersfor tablets, pellets, capsules, suppositories, solutions, emulsions,suspensions, and any other form suitable for use. The active objectcompound is included in the pharmaceutical composition in an amountsufficient to produce the desired effect upon the process or conditionof the disease.

For preparing solid compositions such as tablets, the principal activeingredient may be mixed with a pharmaceutical carrier, e.g.,conventional tableting ingredients such as corn starch, lactose,sucrose, sorbitol, talc, stearic acid, magnesium stearate, dicalciumphosphate or gums, and other pharmaceutical diluents, e.g., water, toform a solid preformulation composition containing a homogeneous mixtureof a compound, or a non-toxic pharmaceutically acceptable salt thereof.When referring to these preformulation compositions as homogeneous, itis meant that the active ingredient is dispersed evenly throughout thecomposition so that the composition may be readily subdivided intoequally effective unit dosage forms such as tablets, pills and capsules.

In solid dosage forms for oral administration (capsules, tablets, pills,dragees, powders, granules and the like), the subject composition ismixed with one or more pharmaceutically acceptable carriers, such assodium citrate or dicalcium phosphate, and/or any of the following: (1)fillers or extenders, such as starches, lactose, sucrose, glucose,mannitol, and/or silicic acid; (2) binders, such as, for example,carboxymethylcellulose, alginates, gelatin, polyvinyl pyrrolidone,sucrose and/or acacia; (3) humectants, such as glycerol; (4)disintegrating agents, such as agar-agar, calcium carbonate, potato ortapioca starch, alginic acid, certain silicates, and sodium carbonate;(5) solution retarding agents, such as paraffin; (6) absorptionaccelerators, such as quaternary ammonium compounds; (7) wetting agents,such as, for example, acetyl alcohol and glycerol monostearate; (8)absorbents, such as kaolin and bentonite clay; (9) lubricants, such atalc, calcium stearate, magnesium stearate, solid polyethylene glycols,sodium lauryl sulfate, and mixtures thereof; and (10) coloring agents.In the case of capsules, tablets and pills, the compositions may alsocomprise buffering agents. Solid compositions of a similar type may alsobe employed as fillers in soft and hard-filled gelatin capsules usingsuch excipients as lactose or milk sugars, as well as high molecularweight polyethylene glycols and the like.

Pharmaceutical compositions suitable for parenteral administrationcomprise a subject composition in combination with one or morepharmaceutically-acceptable sterile isotonic aqueous or non-aqueoussolutions, dispersions, suspensions or emulsions, or sterile powderswhich may be reconstituted into sterile injectable solutions ordispersions just prior to use, which may contain antioxidants, buffers,bacteriostats, solutes which render the formulation isotonic with theblood of the intended recipient or suspending or thickening agents.

Examples of suitable aqueous and non-aqueous carriers which may beemployed in the pharmaceutical compositions include water, ethanol,polyols (such as glycerol, propylene glycol, polyethylene glycol, andthe like), and suitable mixtures thereof, vegetable oils, such as oliveoil, and injectable organic esters, such as ethyl oleate andcyclodextrins. Proper fluidity may be maintained, for example, by theuse of coating materials, such as lecithin, by the maintenance of therequired particle size in the case of dispersions, and by the use ofsurfactants

In another aspect, enteral pharmaceutical formulations including adisclosed conjugate, an enteric material, and a pharmaceuticallyacceptable carrier or excipient thereof are provided. Enteric materialsrefer to polymers that are substantially insoluble in the acidicenvironment of the stomach, and that are predominantly soluble inintestinal fluids at specific pHs. The small intestine is the part ofthe gastrointestinal tract (gut) between the stomach and the largeintestine, and includes the duodenum, jejunum, and ileum. The pH of theduodenum is about 5.5, the pH of the jejunum is about 6.5 and the pH ofthe distal ileum is about 7.5. Accordingly, enteric materials are notsoluble, for example, until a pH of about 5.0, of about 5.2, of about5.4, of about 5.6, of about 5.8, of about 6.0, of about 6.2, of about6.4, of about 6.6, of about 6.8, of about 7.0, of about 7.2, of about7.4, of about 7.6, of about 7.8, of about 8.0, of about 8.2, of about8.4, of about 8.6, of about 8.8, of about 9.0, of about 9.2, of about9.4, of about 9.6, of about 9.8, or of about 10.0. Exemplary entericmaterials include cellulose acetate phthalate (CAP), hydroxypropylmethylcellulose phthalate (HPMCP), polyvinyl acetate phthalate (PVAP),hydroxypropyl methylcellulose acetate succinate (HPMCAS), celluloseacetate trimellitate, hydroxypropyl methylcellulose succinate, celluloseacetate succinate, cellulose acetate hexahydrophthalate, cellulosepropionate phthalate, cellulose acetate maleate, cellulose acetatebutyrate, cellulose acetate propionate, copolymer of methylmethacrylicacid and methyl methacrylate, copolymer of methyl acrylate,methylmethacrylate and methacrylic acid, copolymer of methylvinyl etherand maleic anhydride (Gantrez ES series), ethylmethacrylate-methylmethacrylate-chlorotrimethylammonium ethyl acrylatecopolymer, natural resins such as zein, shellac and copal collophorium,and several commercially available enteric dispersion systems (e. g.,Eudragit L30D55, Eudragit FS30D, Eudragit L100, Eudragit 5100, KollicoatEMM30D, Estacryl 30D, Coateric, and Aquateric). The solubility of eachof the above materials is either known or is readily determinable invitro. The foregoing is a list of possible materials, but one of skillin the art with the benefit of the disclosure would recognize that it isnot comprehensive and that there are other enteric materials that may beused.

Also contemplated herein are methods and compositions that includeadditional active agents, or administering additional active agents.

Certain terms employed in the specification, examples, and appendedclaims are collected here. These definitions should be read in light ofthe entirety of the disclosure and understood as by a person of skill inthe art. Unless defined otherwise, all technical and scientific termsused herein have the same meaning as commonly understood by a person ofordinary skill in the art.

Definitions

In some embodiments, the compounds, as described herein, may besubstituted with any number of substituents or functional moieties. Ingeneral, the term “substituted” whether preceded by the term“optionally” or not, and substituents contained in formulas, refer tothe replacement of hydrogen radicals in a given structure with theradical of a specified substituent.

In some instances, when more than one position in any given structuremay be substituted with more than one substituent selected from aspecified group, the substituent may be either the same or different atevery position.

As used herein, the term “substituted” is contemplated to include allpermissible substituents of organic compounds. In a broad aspect, thepermissible substituents include acyclic and cyclic, branched andunbranched, carbocyclic and heterocyclic, aromatic and non-aromaticsubstituents of organic compounds. In some embodiments, heteroatoms suchas nitrogen may have hydrogen substituents and/or any permissiblesubstituents of organic compounds described herein which satisfy thevalencies of the heteroatoms. Non-limiting examples of substituentsinclude acyl; aliphatic; heteroaliphatic; aryl; heteroaryl; arylalkyl;heteroarylalkyl; alkoxy; cycloalkoxy; heterocyclylalkoxy;heterocyclyloxy; heterocyclyloxyalkyl; alkenyloxy; alkynyloxy; aryloxy;heteroalkoxy; heteroaryloxy; alkylthio; arylthio; heteroalkylthio;heteroarylthio; oxo; —F; —Cl; —Br; —I; —OH; —NO₂; —CN; —SCN; —SR_(x);—CF₃; —CH₂CF₃; —CHCl₂; —CH₂OH; —CH₂CH₂OH; —CH₂NH₂; —CH₂SO₂CH₃; —OR_(x),—C(O)R_(x); —CO₂(R_(x)); —C(O)N(R_(x))₂; —OC(O)R_(x); —OCO₂R_(x);—OC(O)N(R_(x))₂; —N(R_(x))₂; —SOR_(x); —S(O)₂R_(x); —NR_(x)C(O)R_(x); or—C(R_(x))₃; wherein each occurrence of R_(x) independently includes, butis not limited to, hydrogen, aliphatic, heteroaliphatic, aryl,heteroaryl, arylalkyl, or heteroarylalkyl, wherein any of the aliphatic,heteroaliphatic, arylalkyl, or heteroarylalkyl substituents describedabove and herein may be substituted or unsubstituted, branched orunbranched, cyclic or acyclic, and wherein any of the aryl or heteroarylsubstituents described above and herein may be substituted orunsubstituted. Furthermore, the compounds described herein are notintended to be limited in any manner by the permissible substituents oforganic compounds. In some embodiments, combinations of substituents andvariables described herein may be preferably those that result in theformation of stable compounds. The term “stable,” as used herein, refersto compounds which possess stability sufficient to allow manufacture andwhich maintain the integrity of the compound for a sufficient period oftime to be detected and preferably for a sufficient period of time to beuseful for the purposes detailed herein.

The term “acyl,” as used herein, refers to a moiety that includes acarbonyl group. In some embodiments, an acyl group may have a generalformula selected from —C(O)R_(x); —CO₂(R_(x)); —C(O)N(R_(x))₂;—OC(O)R_(x); —OCO₂R_(x); and —OC(O)N(R_(x))₂; wherein each occurrence ofR_(x) independently includes, but is not limited to, hydrogen,aliphatic, heteroaliphatic, aryl, heteroaryl, arylalkyl, orheteroarylalkyl, wherein any of the aliphatic, heteroaliphatic,arylalkyl, or heteroarylalkyl substituents described above and hereinmay be substituted or unsubstituted, branched or unbranched, cyclic oracyclic, and wherein any of the aryl or heteroaryl substituentsdescribed above and herein may be substituted or unsubstituted.

The term “aliphatic,” as used herein, includes both saturated andunsaturated, straight chain (i.e., unbranched), branched, acyclic,cyclic, or polycyclic aliphatic hydrocarbons, which are optionallysubstituted with one or more functional groups. As will be appreciatedby one of ordinary skill in the art, “aliphatic” is intended herein toinclude, but is not limited to, alkyl, alkenyl, alkynyl, cycloalkyl,cycloalkenyl, and cycloalkynyl moieties.

The term “heteroaliphatic,” as used herein, refers to aliphatic moietiesthat contain one or more oxygen, sulfur, nitrogen, phosphorus, orsilicon atoms, e.g., in place of carbon atoms. Heteroaliphatic moietiesmay be branched, unbranched, cyclic or acyclic and include saturated andunsaturated heterocycles such as morpholino, pyrrolidinyl, etc. Incertain embodiments, heteroaliphatic moieties are substituted byindependent replacement of one or more of the hydrogen atoms thereonwith one or more moieties including, but not limited to acyl; aliphatic;heteroaliphatic; aryl; heteroaryl; arylalkyl; heteroarylalkyl; alkoxy;cycloalkoxy; heterocyclylalkoxy; heterocyclyloxy; heterocyclyloxyalkyl;alkenyloxy; alkynyloxy; aryloxy; heteroalkoxy; heteroaryloxy; alkylthio;arylthio; heteroalkylthio; heteroarylthio; oxo; —F; —Cl; —Br; —I; —OH;—NO₂; —CN; —SCN; —SR_(x); —CF₃; —CH₂CF₃; —CHCl₂; —CH₂OH; —CH₂CH₂OH;—CH₂NH₂; —CH₂SO₂CH₃; —OR_(x), —C(O)R_(x); —CO₂(R_(x)); —C(O)N(R_(x))₂;—OC(O)R_(x); —OCO₂R_(x); —OC(O)N(R_(x))₂; —N(R_(x))₂; —SOR_(x);—S(O)₂R_(x); —NR_(x)C(O)R_(x); or —C(R_(x))₃; wherein each occurrence ofR_(x) independently includes, but is not limited to, hydrogen,aliphatic, heteroaliphatic, aryl, heteroaryl, arylalkyl, orheteroarylalkyl, wherein any of the aliphatic, heteroaliphatic,arylalkyl, or heteroarylalkyl substituents described above and hereinmay be substituted or unsubstituted, branched or unbranched, cyclic oracyclic, and wherein any of the aryl or heteroaryl substituentsdescribed above and herein may be substituted or unsubstituted.

In general, the terms “aryl” and “heteroaryl,” as used herein, refer tostable mono- or polycyclic, heterocyclic, polycyclic, andpolyheterocyclic unsaturated moieties having preferably 3-14 carbonatoms, each of which may be substituted or unsubstituted. Substituentsinclude, but are not limited to, any of the previously mentionedsubstituents, i.e., the substituents recited for aliphatic moieties, orfor other moieties as disclosed herein, resulting in the formation of astable compound. In certain embodiments, aryl refers to a mono- orbicyclic carbocyclic ring system having one or two aromatic ringsincluding, but not limited to, phenyl, naphthyl, tetrahydronaphthyl,indanyl, indenyl, and the like. In certain embodiments, the termheteroaryl, as used herein, refers to a cyclic aromatic radical havingfrom five to ten ring atoms of which one ring atom is selected from thegroup consisting of S, O, and N; zero, one, or two ring atoms areadditional heteroatoms independently selected from the group consistingof S, O, and N; and the remaining ring atoms are carbon, the radicalbeing joined to the rest of the molecule via any of the ring atoms, suchas, for example, pyridyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl,imidazolyl, thiazolyl, oxazolyl, isooxazolyl, thiadiazolyl, oxadiazolyl,thiophenyl, furanyl, quinolinyl, isoquinolinyl, and the like. In certainembodiments, any of the above aryl or heteroaryl rings may be fused to aheterocyclic ring.

It will be appreciated that aryl and heteroaryl groups can beunsubstituted or substituted, wherein substitution includes replacementof one, two, three, or more of the hydrogen atoms thereon independentlywith any one or more of the following moieties including, but notlimited to: aliphatic; heteroaliphatic; aryl; heteroaryl; arylalkyl;heteroarylalkyl; alkoxy; cycloalkoxy; heterocyclylalkoxy;heterocyclyloxy; heterocyclyloxyalkyl; alkenyloxy; alkynyloxy; aryloxy;heteroalkoxy; heteroaryloxy; alkylthio; arylthio; heteroalkylthio;heteroarylthio; oxo; —F; —Cl; —Br; —I; —OH; —NO₂; —CN; —CF₃; —CH₂CF₃;—CHCl₂; —CH₂OH; —CH₂CH₂OH; —CH₂NH₂; —CH₂SO₂CH₃; —C(O)R_(x); —CO₂(R_(x));—CON(R_(x))₂; —OC(O)R_(x); —OCO₂R_(x); —OCON(R_(x))₂; —N(R_(x))₂;—S(O)₂R_(x); —NR_(x)(CO)R_(x), wherein each occurrence of R_(x)independently includes, but is not limited to, hydrogen, aliphatic,heteroaliphatic, aryl, heteroaryl, arylalkyl, or heteroarylalkyl,wherein any of the aliphatic, heteroaliphatic, arylalkyl, orheteroarylalkyl substituents described above and herein may besubstituted or unsubstituted, branched or unbranched, cyclic or acyclic,and wherein any of the aryl or heteroaryl substituents described aboveand herein may be substituted or unsubstituted. Additional examples ofgenerally applicable substituents are illustrated by the specificembodiments shown in the Examples that are described herein.

The term “heterocyclic,” as used herein, refers to an aromatic ornon-aromatic, partially unsaturated or fully saturated, 3- to10-membered ring system, which includes single rings of 3 to 8 atoms insize and bi- and tri-cyclic ring systems which may include aromaticfive- or six-membered aryl or aromatic heterocyclic groups fused to anon-aromatic ring. These heterocyclic rings include those having fromone to three heteroatoms independently selected from the groupconsisting of oxygen, sulfur, and nitrogen, in which the nitrogen andsulfur heteroatoms may optionally be oxidized and the nitrogenheteroatom may optionally be quaternized. In certain embodiments, theterm heterocyclic refers to a non-aromatic 5-, 6-, or 7-membered ring ora polycyclic group wherein at least one ring atom is a heteroatomselected from the group consisting of O, S, and N (wherein the nitrogenand sulfur heteroatoms may be optionally oxidized), including, but notlimited to, a bi- or tri-cyclic group, comprising fused six-memberedrings having between one and three heteroatoms independently selectedfrom the group consisting of the oxygen, sulfur, and nitrogen, wherein(i) each 5-membered ring has 0 to 2 double bonds, each 6-membered ringhas 0 to 2 double bonds, and each 7-membered ring has 0 to 3 doublebonds, (ii) the nitrogen and sulfur heteroatoms may be optionallyoxidized, (iii) the nitrogen heteroatom may optionally be quaternized,and (iv) any of the above heterocyclic rings may be fused to an aryl orheteroaryl ring.

The term “alkenyl” as used herein refers to an unsaturated straight orbranched hydrocarbon having at least one carbon-carbon double bond, suchas a straight or branched group of 2-6 or 3-4 carbon atoms, referred toherein for example as C₂₋₆alkenyl, and C₃₋₄alkenyl, respectively.Exemplary alkenyl groups include, but are not limited to, vinyl, allyl,butenyl, pentenyl, etc.

The term “alkenyloxy” used herein refers to a straight or branchedalkenyl group attached to an oxygen (alkenyl-O). Exemplary alkenoxygroups include, but are not limited to, groups with an alkenyl group of3-6 carbon atoms referred to herein as C₃₋₆alkenyloxy. Exemplary“alkenyloxy” groups include, but are not limited to allyloxy,butenyloxy, etc.

The term “alkoxy” as used herein refers to a straight or branched alkylgroup attached to an oxygen (alkyl-O—). Exemplary alkoxy groups include,but are not limited to, groups with an alkyl group of 1-6 or 2-6 carbonatoms, referred to herein as C₁₋₆alkoxy, and C₂-C₆alkoxy, respectively.Exemplary alkoxy groups include, but are not limited to methoxy, ethoxy,isopropoxy, etc.

The term “alkoxycarbonyl” as used herein refers to a straight orbranched alkyl group attached to oxygen, attached to a carbonyl group(alkyl-O—C(O)—). Exemplary alkoxycarbonyl groups include, but are notlimited to, alkoxycarbonyl groups of 1-6 carbon atoms, referred toherein as C₁₋₆alkoxycarbonyl. Exemplary alkoxycarbonyl groups include,but are not limited to, methoxycarbonyl, ethoxycarbonyl,t-butoxycarbonyl, etc.

The term “alkynyloxy” used herein refers to a straight or branchedalkynyl group attached to an oxygen (alkynyl-O)). Exemplary alkynyloxygroups include, but are not limited to, propynyloxy.

The term “alkyl” as used herein refers to a saturated straight orbranched hydrocarbon, for example, such as a straight or branched groupof 1-6, 1-4, or 1-3 carbon atoms, referred to herein as C₁₋₆alkyl,C₁₋₄alkyl, and C₁₋₃alkyl, respectively. Exemplary alkyl groups include,but are not limited to, methyl, ethyl, propyl, isopropyl,2-methyl-1-propyl, 2-methyl-2-propyl, 2-methyl-1-butyl,3-methyl-1-butyl, 3-methyl-2-butyl, 2,2-dimethyl-1-propyl,2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl,2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl,2,2-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, butyl,isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, etc.

The term “alkylcarbonyl” as used herein refers to a straight or branchedalkyl group attached to a carbonyl group (alkyl-C(O)—). Exemplaryalkylcarbonyl groups include, but are not limited to, alkylcarbonylgroups of 1-6 atoms, referred to herein as C₁₋₆alkylcarbonyl groups.Exemplary alkylcarbonyl groups include, but are not limited to, acetyl,propanoyl, isopropanoyl, butanoyl, etc.

The term “alkynyl” as used herein refers to an unsaturated straight orbranched hydrocarbon having at least one carbon-carbon triple bond, suchas a straight or branched group of 2-6, or 3-6 carbon atoms, referred toherein as C₂₋₆alkynyl, and C₃₋₆alkynyl, respectively. Exemplary alkynylgroups include, but are not limited to, ethynyl, propynyl, butynyl,pentynyl, hexynyl, methylpropynyl, etc.

The term “carbonyl” as used herein refers to the radical —C(O)—.

The term “carboxylic acid” as used herein refers to a group of formula—CO₂H.

The term “cyano” as used herein refers to the radical —CN.

The term “cycloalkoxy” as used herein refers to a cycloalkyl groupattached to an oxygen (cycloalkyl-O—).

The term “cycloalkyl” as used herein refers to a monocyclic saturated orpartially unsaturated hydrocarbon group of for example 3-6, or 4-6carbons, referred to herein, e.g., as C₃₋₆cycloalkyl or C₄₋₆cycloalkyland derived from a cycloalkane. Exemplary cycloalkyl groups include, butare not limited to, cyclohexyl, cyclohexenyl, cyclopentyl, cyclobutylor, cyclopropyl.

The terms “halo” or “halogen” as used herein refer to F, Cl, Br, or I.

The term “heterocyclylalkoxy” as used herein refers to aheterocyclyl-alkyl-O— group.

The term “heterocyclyloxyalkyl” refers to a heterocyclyl-O-alkyl- group.

The term “heterocyclyloxy” refers to a heterocyclyl-O— group.

The term “heteroaryloxy” refers to a heteroaryl-O— group.

The terms “hydroxy” and “hydroxyl” as used herein refers to the radical—OH.

The term “oxo” as used herein refers to the radical ═O.

The term “connector” as used herein to refers to an atom or a collectionof atoms optionally used to link interconnecting moieties, such as adisclosed linker and a pharmacophore. Contemplated connectors aregenerally hydrolytically stable.

“Treating” includes any effect, e.g., lessening, reducing, modulating,or eliminating, that results in the improvement of the condition,disease, disorder and the like.

“Pharmaceutically or pharmacologically acceptable” include molecularentities and compositions that do not produce an adverse, allergic, orother untoward reaction when administered to an animal, or a human, asappropriate. For human administration, preparations should meetsterility, pyrogenicity, general safety and purity standards as requiredby FDA Office of Biologics standards.

The term “pharmaceutically acceptable carrier” or “pharmaceuticallyacceptable excipient” as used herein refers to any and all solvents,dispersion media, coatings, isotonic and absorption delaying agents, andthe like, that are compatible with pharmaceutical administration. Theuse of such media and agents for pharmaceutically active substances iswell known in the art. The compositions may also contain other activecompounds providing supplemental, additional, or enhanced therapeuticfunctions.

The term “pharmaceutical composition” as used herein refers to acomposition comprising at least one compound as disclosed hereinformulated together with one or more pharmaceutically acceptablecarriers.

“Individual,” “patient,” or “subject” are used interchangeably andinclude any animal, including mammals, preferably mice, rats, otherrodents, rabbits, dogs, cats, swine, cattle, sheep, horses, or primates,and most preferably humans. The compounds can be administered to amammal, such as a human, but can also be administered to other mammalssuch as an animal in need of veterinary treatment, e.g., domesticanimals (e.g., dogs, cats, and the like), farm animals (e.g., cows,sheep, pigs, horses, and the like) and laboratory animals (e.g., rats,mice, guinea pigs, and the like). The mammal treated is desirably amammal in which treatment of obesity, or weight loss is desired.“Modulation” includes antagonism (e.g., inhibition), agonism, partialantagonism and/or partial agonism.

In the present specification, the term “therapeutically effectiveamount” means the amount of the subject compound that will elicit thebiological or medical response of a tissue, system, animal, or humanthat is being sought by the researcher, veterinarian, medical doctor, orother clinician. The compounds are administered in therapeuticallyeffective amounts to treat a disease. Alternatively, a therapeuticallyeffective amount of a compound is the quantity required to achieve adesired therapeutic and/or prophylactic effect, such as an amount whichresults in weight loss.

The term “pharmaceutically acceptable salt(s)” as used herein refers tosalts of acidic or basic groups that may be present in compounds used inthe present compositions. Compounds included in the present compositionsthat are basic in nature are capable of forming a wide variety of saltswith various inorganic and organic acids. The acids that may be used toprepare pharmaceutically acceptable acid addition salts of such basiccompounds are those that form non-toxic acid addition salts, i.e., saltscontaining pharmacologically acceptable anions, including but notlimited to malate, oxalate, chloride, bromide, iodide, nitrate, sulfate,bisulfate, phosphate, acid phosphate, isonicotinate, acetate, lactate,salicylate, citrate, tartrate, oleate, tannate, pantothenate,bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate,gluconate, glucaronate, saccharate, formate, benzoate, glutamate,methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonateand pamoate (i.e., 1,1′-methylene-bis-(2-hydroxy-3-naphthoate)) salts.Compounds included in the present compositions that are acidic in natureare capable of forming base salts with various pharmacologicallyacceptable cations. Examples of such salts include alkali metal oralkaline earth metal salts and, particularly, calcium, magnesium,sodium, lithium, zinc, potassium, and iron salts. Compounds included inthe present compositions that include a basic or acidic moiety may alsoform pharmaceutically acceptable salts with various amino acids. Thecompounds of the disclosure may contain both acidic and basic groups;for example, one amino and one carboxylic acid group. In such a case,the compound can exist as an acid addition salt, a zwitterion, or a basesalt.

The compounds of the disclosure may contain one or more chiral centersand/or double bonds and, therefore, exist as stereoisomers, such asgeometric isomers, enantiomers, atropisomers, or diastereomers. The term“stereoisomers” when used herein consist of all geometric isomers,enantiomers or diastereomers. These compounds may be designated by thesymbols “R” or “S,” depending on the configuration of substituentsaround the stereogenic carbon atom. Various stereoisomers of thesecompounds and mixtures thereof are encompassed by this disclosure.Stereoisomers include enantiomers and diastereomers. Mixtures ofenantiomers or diastereomers may be designated “(±)” in nomenclature,but the skilled artisan will recognize that a structure may denote achiral center implicitly.

The compounds of the disclosure may contain one or more chiral centersand/or double bonds and, therefore, exist as geometric isomers,enantiomers, atropisomers, or diastereomers. The enantiomers anddiastereomers may be designated by the symbols “(+),” “(−).” “R” or “S,”depending on the configuration of substituents around the stereogeniccarbon atom, but the skilled artisan will recognize that a structure maydenote a chiral center implicitly. Geometric isomers, resulting from thearrangement of substituents around a carbon-carbon double bond orarrangement of substituents around a cycloalkyl or heterocyclic ring,can also exist in the compounds. The symbol

denotes a bond that may be a single, double or triple bond as describedherein. Substituents around a carbon-carbon double bond are designatedas being in the “Z” or “E” configuration wherein the terms “Z” and “E”are used in accordance with IUPAC standards. Unless otherwise specified,structures depicting double bonds encompass both the “E” and “Z”isomers. Substituents around a carbon-carbon double bond alternativelycan be referred to as “cis” or “trans,” where “cis” representssubstituents on the same side of the double bond and “trans” representssubstituents on opposite sides of the double bond. The arrangement ofsubstituents around a carbocyclic ring can also be designated as “cis”or “trans.” The term “cis” represents substituents on the same side ofthe plane of the ring and the term “trans” represents substituents onopposite sides of the plane of the ring. Mixtures of compounds whereinthe substituents are disposed on both the same and opposite sides ofplane of the ring are designated “cis/trans.”

The term “stereoisomers” when used herein consist of all geometricisomers, enantiomers or diastereomers. Various stereoisomers of thesecompounds and mixtures thereof are encompassed by this disclosure.

Individual enantiomers and diastereomers of the compounds can beprepared synthetically from commercially available starting materialsthat contain asymmetric or stereogenic centers, or by preparation ofracemic mixtures followed by resolution methods well known to those ofordinary skill in the art. These methods of resolution are exemplifiedby (1) attachment of a mixture of enantiomers to a chiral auxiliary,separation of the resulting mixture of diastereomers byrecrystallization or chromatography and liberation of the optically pureproduct from the auxiliary, (2) salt formation employing an opticallyactive resolving agent, (3) direct separation of the mixture of opticalenantiomers on chiral liquid chromatographic columns or (4) kineticresolution using stereoselective chemical or enzymatic reagents. Racemicmixtures can also be resolved into their component enantiomers bywell-known methods, such as chiral-phase gas chromatography orcrystallizing the compound in a chiral solvent. Stereoselectivesyntheses, a chemical or enzymatic reaction in which a single reactantforms an unequal mixture of stereoisomers during the creation of a newstereocenter or during the transformation of a pre-existing one, arewell known in the art. Stereoselective syntheses encompass both enantio-and diastereoselective transformations. For examples, see Carreira andKvaerno, Classics in Stereoselective Synthesis, Wiley-VCH: Weinheim,2009.

The compounds disclosed herein can exist in solvated as well asunsolvated forms with pharmaceutically acceptable solvents such aswater, ethanol, and the like. In one embodiment, the compound isamorphous. In one embodiment, the compound is a polymorph. In anotherembodiment, the compound is in a crystalline form.

Also embraced are isotopically labeled compounds which are identical tothose recited herein, except that one or more atoms are replaced by anatom having an atomic mass or mass number different from the atomic massor mass number usually found in nature. Examples of isotopes that can beincorporated into the compounds include isotopes of hydrogen, carbon,nitrogen, oxygen, phosphorus, sulfur, fluorine and chlorine, such as ²H,³H, ¹³C, ¹⁴C, ¹⁵N, ¹⁸O, ¹⁷O, ³¹P, ³²P, ³⁵S, ¹⁸F, ¹⁰B, and ³⁶C1,respectively. For example, a compound may have one or more H atomreplaced with deuterium.

Certain isotopically-labeled disclosed compounds (e.g., those labeledwith ³H and ¹⁴C) are useful in compound and/or substrate tissuedistribution assays. Tritiated (i.e., ³H) and carbon-14 (i.e., ¹⁴C)isotopes are particularly preferred for their ease of preparation anddetectability. Further, substitution with heavier isotopes such asdeuterium (i.e., ²H) may afford certain therapeutic advantages resultingfrom greater metabolic stability (e.g., increased in vivo half-life orreduced dosage requirements) and hence may be preferred in somecircumstances. Isotopically labeled compounds can generally be preparedby following procedures analogous to those disclosed in the Examplesherein by substituting an isotopically labeled reagent for anon-isotopically labeled reagent.

The term “prodrug” refers to compounds that are transformed in vivo toyield a disclosed compound or a pharmaceutically acceptable salt,hydrate or solvate of the compound. The transformation may occur byvarious mechanisms (such as by esterase, amidase, phosphatase, oxidativeand or reductive metabolism) in various locations (such as in theintestinal lumen or upon transit of the intestine, blood, or liver).Prodrugs are well known in the art (for example, see Rautio,Kumpulainen, et al, Nature Reviews Drug Discovery 2008, 7, 255). Forexample, if a compound or a pharmaceutically acceptable salt, hydrate,or solvate of the compound contains a carboxylic acid functional group,a prodrug can comprise an ester formed by the replacement of thehydrogen atom of the acid group with a group such as (C₁₋₈)alkyl,(C₂₋₁₂)alkanoyloxymethyl, 1-(alkanoyloxy)ethyl having from 4 to 9 carbonatoms, 1-methyl-1-(alkanoyloxy)-ethyl having from 5 to 10 carbon atoms,alkoxycarbonyloxymethyl having from 3 to 6 carbon atoms,1-(alkoxycarbonyloxy)ethyl having from 4 to 7 carbon atoms,1-methyl-1-(alkoxycarbonyloxy)ethyl having from 5 to 8 carbon atoms,N-(alkoxycarbonyl)aminomethyl having from 3 to 9 carbon atoms,1-(N-(alkoxycarbonyl)amino)ethyl having from 4 to 10 carbon atoms,3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl,di-N,N—(C₁-C₂)alkylamino(C₂-C₃)alkyl (such as β-dimethylaminoethyl),carbamoyl-(C₁-C₂)alkyl, N,N-di(C₁-C₂)alkylcarbamoyl-(C₁-C₂)alkyl andpiperidino-, pyrrolidino- or morpholino(C₂-C₃)alkyl.

Similarly, if a compound contains an alcohol functional group, a prodrugcan be formed by the replacement of the hydrogen atom of the alcoholgroup with a group such as (C₁₋₆)alkanoyloxymethyl,1-((C₁₋₆)alkanoyloxy)ethyl,1-methyl-1-((C₁₋₆)alkanoyloxy)ethyl(C₁₋₆)alkoxycarbonyloxymethyl,N—(C₁₋₆)alkoxycarbonylaminomethyl, succinoyl, (C₁₋₆)alkanoyl,α-amino(C₁₋₄)alkanoyl, arylacyl and α-aminoacyl, orα-aminoacyl-α-aminoacyl, where each α-aminoacyl group is independentlyselected from the naturally occurring L-amino acids, P(O)(OH)₂,—P(O)(O(C₁-C₆)alkyl)₂ or glycosyl (the radical resulting from theremoval of a hydroxyl group of the hemiacetal form of a carbohydrate).

If a compound incorporates an amine functional group, a prodrug can beformed, for example, by creation of an amide or carbamate, anN-acyloxyalkyl derivative, an (oxodioxolenyl)methyl derivative, anN-Mannich base, imine, or enamine. In addition, a secondary amine can bemetabolically cleaved to generate a bioactive primary amine, or atertiary amine can be metabolically cleaved to generate a bioactiveprimary or secondary amine. For examples, see Simplício et al.,Molecules 2008, 13, 519 and references therein.

EXAMPLES

The compounds described herein can be prepared in a number of ways basedon the teachings contained herein and synthetic procedures known in theart. In the description of the synthetic methods described below, it isto be understood that all proposed reaction conditions, including choiceof solvent, reaction atmosphere, reaction temperature, duration of theexperiment and workup procedures, can be chosen to be the conditionsstandard for that reaction, unless otherwise indicated. It is understoodby one skilled in the art of organic synthesis that the functionalitypresent on various portions of the molecule should be compatible withthe reagents and reactions proposed. Substituents not compatible withthe reaction conditions will be apparent to one skilled in the art, andalternate methods are therefore indicated. The starting materials forthe examples are either commercially available or are readily preparedby standard methods from known materials.

Liquid Chromatography Mass Spectrometry (LCMS) was performed on a WatersAcquity UPLC/SQD2 mass spectrometer under the following parameters:Column: ACE Excel 2 SuperC18; Length:100 mm; Diameter: 2.1 mm; poresize: 2.0 μm; Column temp: 40° C., Sample temp: 25° C. or 37° C.Gradient elution methods and mobile phase eluents are shown below.

polar_3min_0_1500 (0.8 mL/min flow) Time (min) Solvent A (%) Solvent B(%) 0 95 5 0.2 95 5 1.50 10 90 2.00 10 90 2.20 95 5 3.00 95 5

non_polar_3min (0.8 mL/min flow) Time (min) Solvent A (%) Solvent B (%)0 85 15 0.2 85 15 1.60 1 99 2.20 1 99 2.80 85 15 3.00 85 15

Acidic mobile phase eluents were Solvent A (0.1% formic acid in water,pH=2.6) and Solvent B (0.1% formic acid in acetonitrile, pH=2.6).

Basic mobile phase eluents were Solvent A (0.1% NH₄OH in water,pH=10.63) and Solvent B (100% acetonitrile).

Neutral mobile phase eluents were Solvent A (5 mM ammonium formate inwater, pH=7.7) and Solvent B (100% acetonitrile).

Slightly acidic mobile phase eluents were Solvent A (10 mM ammoniumacetate in water, pH=6.33) and Solvent B (100% acetonitrile).

Preparative High-performance liquid chromatography (HPLC) was performedon a Waters 2489 HPLC equipped with a UV/Vis detector, 2545 BinaryGradient Module, and Waters Fraction Collector III using ChromScopesoftware and under the following conditions: Preparative column: XBridgePrep C18 5 mm; OBD 19×250 mm column; Column temp: 25° C.; Sample temp:25° C. Neutral mobile phase eluents were Solvent A (10 mM Ammoniumbicarbonate in water, 5% acetonitrile, pH=7.4, degassed) and Solvent B(100% acetonitrile, degassed). Gradient elution methods and mobile phaseeluents are shown below.

Preparative HPLC gradient 1 Time (min) Flow (mL/min) Solvent A (%)Solvent B (%) Initial 18 95 5 5 18 90 10 20 18 40 60 25 18 20 80 30 1810 90 35 18 5 95 40 18 95 5

Preparative HPLC gradient 2 Time (min) Flow (mL/min) Solvent A (%)Solvent B (%) Initial 20 80 20 2 20 60 40 5 20 50 50 10 20 40 60 20 2020 80 35 20 20 80 45 20 20 80 50 20 15 85 60 20 5 95 65 20 5 95 80 20 595 100 20 90 10

Preparative HPLC gradient 3 Time (min) Flow (mL/min) Solvent A (%)Solvent B (%) Initial 18 95 5 5 18 90 10 20 18 70 30 30 18 50 50 40 1840 60 45 18 20 80 50 18 10 90 55 18 5 95 60 18 95 5

Preparative HPLC gradient 4 Time (min) Flow (mL/min) Solvent A (%)Solvent B (%) Initial 18 95 5 5 18 90 10 10 18 80 20 20 18 70 30 30 1860 40 40 18 50 50 45 18 70 30 50 18 5 95 55 18 95 5

Example 1 and Example 6

4-(1,1,3,3-Tetramethyl-3-phenyldisiloxanyl)butan-1-ol [Example 6]

A solution of 4-(1,1,3,3-tetramethyl-3-phenyldisiloxanyl)butanoic acid(1 g, 3.37 mmol) in THF (20 mL) was charged with borane-DMS (0.96 mL,10.1 mmol) dropwise at room temperature under nitrogen atmosphere andstirred further for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 10-15% ethyl acetate inn-hexane to afford 805 mg, 85% yield of the title compound as colorlessoil. ¹H NMR (400 MHz, DMSO-d₆) δ=7.49 (d, J=3.42 Hz, 2H), 7.28-7.40 (m,3H), 4.24 (t, J=4.40 Hz, 1H), 3.31 (d, J=5.38 Hz, 2H), 1.21-1.44 (m,4H), 0.43-0.51 (m, 2H), 0.26 (s, 6H), 0.00 (s, 6H). ¹H NMR (400 MHz,CDCl₃) δ=7.54 (d, J=3.42 Hz, 2H), 7.35-7.40 (m, 3H), 3.17 (q, J=6.68 Hz,2H), 1.94 (s, 3H), 1.43-1.52 (m, 2H), 0.47-0.55 (m, 2H), 0.33 (s, 6H),0.07 (s, 6H); MS (ES⁺): m/z=263.91 [M−18]; LCMS: t_(R)=3.71 min.

4-(1,1,3,3-Tetramethyl-3-phenyldisiloxanyl)butanoic Acid [Example 1]

A solution of 4-(chlorodimethylsilyl)butanoic acid (2.3 g, 12.7 mmol) inacetonitrile (115 mL) was charged with dimethyl(phenyl)silanol (969 mg,6.36 mmol) and stirred at room temperature for 2 h. The reaction mixturewas concentrated in vacuo, dissolved in diethyl ether (40 mL) andconcentrated resulting in the crude compound which was purified bycolumn chromatography on silica gel eluting with 40-70% ethyl acetate inn-hexane to afford 900 mg, 24% yield, of the title compound as colorlessoil. ¹H NMR (400 MHz, DMSO-d₆) δ=11.91 (br. s, 1H), 7.46-7.51 (m, 2H),7.28-7.37 (m, 3H), 2.15 (t, J=7.09 Hz, 2H), 1.42-1.53 (m, 2H), 0.44-0.52(m, 2H), 0.25 (s, 6H), −0.03 (s, 6H). ¹H NMR (400 MHz, CDCl₃) δ=7.54 (d,J=3.42 Hz, 2H), 7.33-7.41 (m, 3H), 2.35 (t, J=7.34 Hz, 2H), 1.66 (td,J=7.70, 15.90 Hz, 2H), 0.54-0.63 (m, 2H), 0.32 (s, 6H), 0.07 (s, 6H); MS(ES+): m/z=295.00 [M−H]; LCMS: t_(R)=2.13 min.

4-(Chlorodimethylsilyl)butanoic Acid (2)

A solution of 4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)dibutyricacid (2 g, 6.52 mmol) in 4M HCl in dioxane (60 mL) was stirred at roomtemperature for 2 h. The reaction mixture was concentrated in vacuoresulting in 2.35 g of crude compound as colorless oil. The crudecompound was used in the next step without further purification. ¹H NMR(400 MHz, DMSO-d₆) δ=2.22 (t, J=7.09 Hz, 2H), 1.50-1.55 (m, 2H),0.45-0.56 (m, 2H), 0.05 (s, 6H).

Example 2 and Example 3

4-(1,1,3,3-tetramethyl-3-phenyldisiloxanyl)butanamide [Example 2]

A solution of HCl-dioxane (5N, 5 mL) was added to a solution of compound1 (3.0 g, 9.8 mmol) in dioxane (7 mL) at room temperature. The reactionmixture was stirred for 2 h. The solvent was removed under reducedpressure. The residue was azeotroped with ACN (5 mL×2) to remove theexcessive acid, and then dissolved in ACN (4 mL),chlorodimethylphenylsilane (5.0 g, 29.4 mmol) and H₂O (0.5 mL) wereadded in sequence. The reaction mixture was stirred at room temperaturefor 2 h, then concentrated. The crude product was purified by prep-HPLCto afford 350 mg, 10% yield of the title compound. ¹H NMR (400 MHz,DMSO-d6): δ 7.45-7.50 (m, 2H), 7.32-7.40 (m, 3H), 7.16 (bs, 1H), 6.65(bs, 1H), 1.98 (t, J=8.2 Hz, 2H), 1.45 (m, 2H), 0.45 (m, 2H), 0.25 (s,6H), 0.00 (s, 6H). ESI for C₁₄H₂₅NO₂Si₂. Found 296.33 [M+H]⁺.

4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)dibutanamide (1)

HATU (9.3 g, 29.8 mmol) was added to a solution of1,3-bis(3-carboxypropyl)tetramethyldisiloxane (3.06 g, 9.8 mmol) andammonium chloride (1.3 g, 29.8 mmol) in DMF (50 mL) at room temperature.The pH was adjusted to 8-9 with DIPEA (3-5 mL), then the reactionmixture was stirred at room temperature for 12 h, then quenched withwater (200 mL). The mixture was stirred for 3 h, then filtrated. Thesolid was collected, washed with water (20 mL×5), dried, andconcentrated to dryness. The crude product was purified by columnchromatography on silica gel (DCM:MeOH=20:1 to 10:1) to afford 5.1 g,˜100% yield of the title compound.

Methyl 4-(3-(4-amino-4-oxobutyl)-1,1,3,3-tetramethyldisiloxanyl)benzoate[Example 3]

A solution of HCl-dioxane (5N, 10 mL) was added to a mixture of compound2 (3.0 g, 11.2 mmol) and 1,3-bis(3-carboxypropyl)tetramethyl disiloxane(3.4 g, 11 mmol) in dioxane (5 mL) at room temperature. The reactionmixture was stirred for 2 h. The solvent was removed under reducedpressure then the residue was dissolved in MeCN (10 mL), followed by theaddition of H₂O (˜0.5 mL). The mixture was stirred for 3 h. The solventwas concentrated in vacuo and the crude product was purified byprep-HPLC to afford 500 mg, 12% yield of the title compound. ¹H NMR (400MHz, DMSO-d6): δ 7.90 (d, J=8.4 Hz, 2H), 7.63 (d, J=8.4 Hz, 2H), 7.17(bs, 1H), 6.65 (bs, 1H), 3.81 (s, 3H), 1.94 (m, 2H), 1.45 (m, 2H), 0.45(m, 2H), 0.25 (s, 6H), 0.00 (s, 6H). ESI for C₁₆H₂₇NO₄Si₂. Found 354.73[M+H]⁺.

Example 4 and Example 18

N-(3-(1,1,3,3-Tetramethyl-3-phenyldisiloxanyl)propyl)acetamide [Example4]

A solution of N-(3-(chlorodimethylsilyl)propyl)acetamide (3 g, 15.4mmol) in acetonitrile (150 mL) was charged with dimethyl(phenyl)silanol(1.17 g, 7.74 mmol) and stirred at room temperature for 2 h. Thereaction mixture was concentrated in vacuo, dissolved in diethyl etherand concentrated resulting in the crude compound which was purified bycolumn chromatography on silica gel eluting with 40-70% ethyl acetate inn-hexane to afford 2 g, 42% yield of the title compound as colorlessoil. ¹H NMR (400 MHz, DMSO-d₆) δ=7.74 (br. s, 1H), 7.46-7.51 (m, 2H),7.31-7.37 (m, 3H), 2.92 (q, J=6.68 Hz, 2H), 1.73 (s, 3H), 1.34 (td,J=7.70, 15.90 Hz, 2H), 0.41-0.48 (m, 2H), 0.26 (s, 6H), 0.00 (s, 6H), ¹HNMR (400 MHz, CDCl₃) δ=7.54 (d, J=3.42 Hz, 2H), 7.35-7.40 (m, 3H), 3.17(q, J=6.68 Hz, 2H), 1.94 (s, 3H), 1.43-1.52 (m, 2H), 0.47-0.55 (m, 2H),0.33 (s, 6H), 0.07 (s, 6H); MS (ES+): m/z=310.00 [M+H]⁺; LCMS:t_(R)=3.08 min.

N-(3-(Chlorodimethylsilyl)propyl)acetamide (2)

A solution ofN,N-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(2.6 g, 7.81 mmol) in dioxane: HCl (4M, 78 mL) was stirred at roomtemperature for 2 h. The reaction mixture was concentrated in vacuoresulting in 3.02 g of crude compound as colorless oil. The crudecompound was used in the next step without further purification. ¹H NMR(400 MHz, DMSO-d₆) δ=7.89 (br. s, 1H), 2.99 (d, J=5.38 Hz, 2H), 1.80 (s,3H), 1.39 (td, J=7.83, 15.65 Hz, 2H), 0.44-0.50 (m, 2H), 0.05 (s, 6H).

N,N′-((1,1,3,3-Tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide[Example 18]

A solution of3,3′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (2 g,8.04 mmol) in diethyl ether (100 mL) at 0° C. was charged with triethylamine (2.8 mL, 20.1 mmol) and acetyl chloride (1.4 mL, 19.2 mmol) andstirred at room temperature for 1 h. The solid precipitated wasfiltered, washed with diethyl ether and the filtrate was concentrated invacuo resulting in 2.67 g of the title compound as colorless oil. Thecrude compound was used in the next step without further purification.¹H NMR (400 MHz, DMSO-d₆) δ=7.77 (br. s, 2H), 2.94 (d, J=6.36 Hz, 4H),1.69-1.83 (m, 6H), 1.35 (d, J=6.85 Hz, 4H), 0.36-0.50 (m, 4H), 0.00 (s,12H), ¹H NMR (400 MHz, CDCl₃) δ=6.04 (br. s, 1H), 3.21 (q, J=6.68 Hz,4H), 1.93-2.07 (m, 6H), 1.53 (td, J=7.83, 15.65 Hz, 4H), 0.46-0.55 (m,4H), 0.05 (s, 12H); MS (ESMS+): m/z=355.05 [M+Na]⁺; ESMS: t_(R)=0.13min, m/z=377.00 [M+2Na]⁺; ESMS: t_(R)=0.15 min; MS (ES⁺): m/z=333.00[M+H]⁺; LCMS: t_(R)=2.07 min.

Synthetic Scheme: Example 5 and Example 91

N-(3-(1,1,3,3-Tetramethyl-3-((thiazol-2-ylthio)methyl)disiloxanyl)propyl)acetamide[Example 5]

A solution of2-(((3-(chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)thiazole(1 g, 3.210 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(1.03 g, 3.210 mmol) in 4M HCl in dioxane (20 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 5 and 6. The mixture of intermediate5 and 6 was dissolved in acetonitrile (20 mL) and followed by additionof water (0.23 mL, 12.86 mmol), DIPEA (3.34 mL, 19.29 mmol) and stirredat room temperature for 1 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by Combi Flashchromatography on silica gel eluting with 0-10% methanol in DCM toafford 535 mg, 46% yield, of the title compound as colorless oil. ¹H NMR(400 MHz, DMSO-d₆) δ=7.76 (br. s, 1H), 7.66 (d, J=3.42 Hz, 1H), 7.60 (d,J=3.42 Hz, 1H), 2.96 (q, J=6.52 Hz, 2H), 1.75 (s, 3H), 1.32-1.42 (m,2H), 0.44-0.50 (m, 2H), 0.17 (s, 6H), 0.05 (s, 6H) 2H protons merged insolvent peak. ¹H NMR (400 MHz, CDCl₃) δ=7.64 (d, J=2.45 Hz, 1H), 7.20(d, J=2.93 Hz, 1H), 3.22 (q, J=6.68 Hz, 2H), 2.50 (s, 2H), 1.96 (s, 3H),1.60-1.65 (m, 2H), 0.51-0.59 (m, 2H), 0.23 (s, 6H), 0.10 (s, 6H), MS(ES⁺): m/z=363.05 [M+H]⁺; LCMS: t_(R)=3.16 min.

2-(((3-(Chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)thiazole[Example 91]

A solution of thiazole-2-thiol (2 g, 17.09 mmol) in acetonitrile (50 mL)was added potassium carbonate (4.7 g, 34.18 mmol) and1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane (5.92 g, 25.64 mmol)at room temperature. The reaction mixture was further heated to 60° C.and stirred for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by Combi Flashchromatography on silica gel eluting with 10-20% ethyl acetate inn-hexane to afford 3.4 g, 65% yield, of the title compound as colorlessoil. ¹H NMR (400 MHz, DMSO-d₆) δ=7.68 (d, J=3.42 Hz, 1H), 7.61 (d,J=3.42 Hz, 1H), 2.87 (s, 2H), 2.53 (s, 2H), 0.21 (s, 6H), 0.17 (s, 6H);MS (ES⁺): m/z=312.00 [M+H]⁺; LCMS: t_(R)=4.15 min.

Example 7, Example 22, Example 23, and Example 25

4-(3-(4-ethoxy-4-oxobutyl)-1,1,3,3-tetramethyldisiloxanyl)butanoic acid[Example 7]

A solution of HCl-dioxane (5N, 5 mL) was added to a mixture of compound1 (1.6 g, 5.5 mmol) and Example 25 (2.01 g, 5.5 mmol) in dioxane (5 mL)at room temperature. The mixture was stirred for 2 h. The solvent wasremoved under reduced pressure, and the residue was azeotroped with ACN(5 mL×2) to remove the excessive acid, then dissolved in ACN (4 mL),followed by the addition of 5 drops of water (ca. 0.2 mL). The mixturewas stirred for 0.5 h. The reaction was complete by LC-MS analysis. Theresulting mixture was eluted with EtOAc (50 mL), then washed with brine(30 mL×3), dried and concentrated to dryness. The residue was purifiedby column chromatography on silica gel (hexane:EtOAc=10:1 to 5:1) toafford the desired compound (750 mg, 41% yield). ¹H NMR (400 MHz,CDCl₃): δ 4.07 (m, 2H), 2.30 (m, 2H), 2.26 (m, 2H), 1.57-1.63 (m, 4H),1.19 (m, 3H), 0.45-0.53 (m, 4H), 0.01-0.09 (m, 12H). ESI forC₁₄H₃₀O₅Si₂. Found 357.32 [M+Na]⁺

4-(3-(4-(benzyloxy)-4-oxobutyl)-1,1,3,3-tetramethyldisiloxanyl)butanoicacid[Example 22]

Compound Example 22 (890 mg, 55% yield) was prepared from compound 1 andExample 23 following the same procedure for Example 6. ¹H NMR (300 MHz,CDCl3): δ 7.36 (m, 5H), 5.14 (s, 2H), 2.36-2.43 (m, 4H), 1.64-1.69 (m,4H), 0.52-0.59 (m, 4H), 0.04-0.09 (m, 12H). ESI for C19H32O5Si2. Found395.5 [M−H]−

Dibenzyl 4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)dibutyrate[Example 23]

To a solution of compound 1 (2.01 g, 6.5 mmol) in ACN (20 mL) was addedK₂CO₃ (1.80 g, 13 mmol) at room temperature. The mixture was heated toreflux at 60° C. for 1 h. BnBr (2.20 g, 13 mmol) was added to themixture and refluxed for another 1 h. Solid was filtered after thereaction was cooled to room temperature. The filtrate was diluted withEtOAc (50 mL), washed with brine (50 mL×2) and dried over anhydrousNa₂SO₄. The solvent was removed under reduced pressure. Crude productwas purified by column chromatography on silica gel (hexane:EtOAc=100:1to 80:1) to afford the desired product (2.41 g, 75% yield). ¹H NMR (400MHz, CDCl₃): δ 7.30 (m, 10H), 5.07 (s, 4H), 2.33 (m, 4H), 1.62 (m, 4H),0.48 (m, 4H), 0.01 (m, 12H). ESI for C₂₆H₃₈O₅Si₂. Found 509.5 [M+Na]⁺

Diethyl 4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)dibutyrate [Example25]

To a solution of compound 1 (4.00 g, 13 mmol) in ACN (40 mL) was addedK2CO3 (3.62 g, 26 mmol) at room temperature. The mixture was heatedunder reflux at 60° C. and stirred for 1 h. The mixture was cooled to40° C., and iodoethane (4.10 g, 26 mmol) was added carefully. Thereaction mixture was further heated under reflux and stirred for 2 h.The reaction mixture was cooled to room temperature and then filtered toremove the solid. The filtrate was concentrated to dryness. The residuewas purified by column chromatography on silica gel (hexane:EtOAc=80:1)to afford the desired product (600 mg, 12% yield). ¹H NMR (400 MHz,CDCl₃): δ 4.06 (m, 4H), 2.26 (m, 4H), 1.59 (m, 4H), 1.20 (m, 4H), 0.89(m, 12H). ESI for C₁₆H₃₄O₅Si₂. Found 385.29 [M+Na]⁺

Example 8

2-(((1,1,3,3,3-Pentamethyldisiloxanyl)methyl)thio)pyrimidine [Example 8]

A solution of pyrimidine-2-thiol (2 g, 17.8 mmol) in acetonitrile (60mL) was charged with potassium carbonate (3.69 g, 26.7 mmol) and1-(chloromethyl)-1,1,3,3,3-pentamethyldisiloxane 2 (3.86 g, 19.6 mmol)at room temperature and was further heated to 55° C. for 3 h. Thereaction mixture was concentrated in vacuo, diluted with diethyl etherand stirred for 15 min. The solid precipitated was filtered and thefiltrate was concentrated in vacuo resulting in the crude compound whichwas purified by column chromatography on silica gel eluting with 0-5%ethyl acetate in n-hexane to afford 3 g, 62% yield, of the titlecompound as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.55 (d, J=4.89Hz, 2H), 7.12 (t, J=4.65 Hz, 1H), 2.31 (s, 2H), 0.09 (s, 6H), 0.00 (s,9H); MS (ES⁺): m/z=273.05 [M+H]⁺; LCMS: t_(R)=3.46 min.

Example 9

24,6-Dimethyl-2-(((1,1,3,3,3-pentamethyldisiloxanyl)methyl)thio)pyrimidine[Example 9]

A solution of 4,6-dimethylpyrimidine-2-thiol (2 g, 14.2 mmol) inacetonitrile (60 mL) was charged with potassium carbonate (2.95 g, 21.3mmol) and 1-(chloromethyl)-1,1,3,3,3-pentamethyldisiloxane 2 (3.08 g,15.6 mmol) at room temperature and was further heated to 55° C. for 3 h.The reaction mixture was concentrated in vacuo, diluted with diethylether and stirred for 15 min. The solid precipitated was filtered andthe filtrate was concentrated in vacuo resulting in the crude compoundwhich was purified by column chromatography on silica gel eluting with0-5% ethyl acetate in n-hexane to afford 3.5 g, 82% yield, of the titlecompound as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=6.85 (s, 1H),2.26 (s, 8H), 0.07 (s, 6H), 0.00 (s, 9H); MS (ES⁺): m/z=301.05 [M+H]⁺;LCMS: t_(R)=3.81 min.

Example 10

2-(((1,1,3,3,3-Pentamethyldisiloxanyl)methyl)sulfonyl)pyrimidine[Example 10]

A solution of2-(((1,1,3,3,3-pentamethyldisiloxanyl)methyl)thio)pyrimidine (2 g, 17.8mmol) in DCM (30 mL) was charged with 3-chlorobenzoperoxoic acid (3.86g, 19.6 mmol) in lots over a period of 15 min at room temperature andfurther stirred for 30 min. The reaction mixture was washed withsaturated sodium bicarbonate solution and the organic layer wasseparated. The separated organic layers were dried over anhydrousNa₂SO₄, filtered and concentrated in vacuo resulting in the crudecompound which was purified by column chromatography on silica geleluting with 20-50% ethyl acetate in n-hexane to afford 1.4 g, 84%yield, of the title compound as a colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=9.01 (d, J=4.40 Hz, 2H), 7.76 (t, J=4.89 Hz, 1H), 3.26 (s,3H), 0.22 (s, 6H), 0.00 (s, 9H).

¹H NMR (400 MHz, CDCl₃) δ=8.94 (d, J=4.40 Hz, 2H), 7.52 (t, J=4.40 Hz,1H), 3.21 (s, 2H), 0.42 (s, 6H), 0.11 (s, 9H); MS (ES⁺): m/z=305.00[M+H]⁺; LCMS: t_(R)=3.17 min.

Example 11

2-((1,1,3,3,3-Pentamethyldisiloxanyl)methoxy)pyrimidine [Example 11]

A solution of triethyl amine (0.18 mL, 1.28 mmol) and trimethylsilanol(154 mg, 1.71 mmol) was charged with2-((chlorodimethylsilyl)methoxy)pyrimidine (173 mg, 0.85 mmol) inacetonitrile (3 mL) and stirred at room temperature for 2 h. Thereaction mixture was concentrated in vacuo, dissolved in diethyl etherand concentrated resulting in the crude compound which was purified bycolumn chromatography on silica gel eluting with 5-15% ethyl acetate inn-hexane to afford 150 mg, 68% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.53 (d, J=4.40 Hz, 2H), 7.05(t, J=4.89 Hz, 1H), 3.93 (s, 2H), 0.11 (s, 6H), 0.00 (s, 9H); MS (ES⁺):m/z=257.08 [M+H]⁺; LCMS: t_(R)=3.55 min.

2-((Chlorodimethylsilyl)methoxy)pyrimidine (1)

A solution of1,1,3,3-tetramethyl-1,3-bis((pyrimidin-2-yloxy)methyl)disiloxane (300mg, 0.85 mmol) in dioxane: HCl (4M, 3 mL) was stirred at roomtemperature for 2 h. The reaction mixture was concentrated in vacuoresulting in 173 mg of crude compound as colorless oil. The crudecompound was used in the next step without further purification. ¹H NMR(400 MHz, DMSO-d₆) δ=8.80 (d, J=4.89 Hz, 1H), 7.53-7.59 (m, 1H), 7.38(d, J=5.38 Hz, 1H), 2.48 (br. s, 2H), 0.34 (s, 3H), 0.24 (s, 3H); MS(ES⁺): m/z=289.03 [M+ACN+2Na]⁺; LCMS: t_(R)=3.76 min.

Example 12, Example 13, and Example 14

2-(2-(1,1,3,3-Tetramethyl-3-phenyldisiloxanyl)ethyl)pyrimidine [Example12]

A mixture of(E)-2-(2-(1,1,3,3-tetramethyl-3-phenyldisiloxanyl)vinyl)pyrimidine and(Z)-2-(2-(1,1,3,3-tetramethyl-3-phenyldisiloxanyl)vinyl)pyrimidine (400mg, 1.27 mmol) in THF (4 mL) was charged with ethoxydimethylsilane (397mg, 3.81 mmol), palladium acetate (28 mg, 0.13 mmol) and under argonatmosphere at room temperature for 30 min. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 0-35% ethyl acetatein n-hexane to afford 350 mg, 87% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.65 (d, J=4.89 Hz, 2H),7.46-7.50 (m, 2H), 7.31-7.35 (m, 3H), 7.25 (t, J=4.89 Hz, 1H), 2.80-2.85(m, 2H), 0.95-1.00 (m, 2H), 0.25 (s, 6H), 0.00 (s, 6H); MS (ES⁺):m/z=317.05 [M+H]⁺; LCMS: t_(R)=3.79 min.

(E)-2-(2-(1,1,3,3-Tetramethyl-3-phenyldisiloxanyl)vinyl)pyrimidine[Example 13]

A solution of 2-ethynylpyrimidine (2 g, 19.2 mmol) in toluene (20 mL)was charged with 1,1,3,3-tetramethyl-1-phenyldisiloxane (4.04 g, 19.2mmol) was purged with argon for 30 min. To the resulting solution wasadded 2% solution of 1,1,3,3-tetramethyldivinyl disiloxane platinum(0)complex in xylene (23 mL, 0.96 mmol) and stirred at room temperature for2 h. The reaction mixture was heated to 90° C. for 4 h. The reactionmixture was concentrated in vacuo resulting in the crude compound whichwas purified by column chromatography on silica gel eluting with 0-10%ethyl acetate in n-hexane to afford 2.71 g, 45% yield, of a colorlessoil of the title compound as a mixture of cis & trans. ¹H NMR (400 MHz,DMSO-d₆) δ=8.80 (br. s, 2H), 7.55 (br. s, 2H), 7.26-7.43 (m, 5H), 6.99(d, J=19.07 Hz, 1H), 0.34 (br. s, 6H), 0.24 (br. s, 6H); MS (ES⁺):m/z=315.12 [M+H]⁺; LCMS: t_(R)=3.81 min.

2-(2-(1,1,3,3-Tetramethyl-3-phenyldisiloxanyl)ethyl)hexahydropyrimidine[Example14]

A mixture of(E)-2-(2-(1,1,3,3-tetramethyl-3-phenyldisiloxanyl)vinyl)pyrimidine and(Z)-2-(2-(1,1,3,3-tetramethyl-3-phenyldisiloxanyl)vinyl)pyrimidine (300mg, 0.95 mmol) in DCM (6 mL) was charged with 10% Pd/C (30 mg, 10% w/w)and under argon atmosphere at room temperature. The resulting solutionwas stirred under hydrogen atmosphere at room temperature for 6 h. Thereaction mixture was filtered through a pad of Celite and the filtratewas concentrated in vacuo resulting in the crude compound which waspurified by column chromatography on silica gel eluting with 0-35% ethylacetate in n-hexane to afford 261 mg, 85% yield, of the title compoundas white semi solid. ¹H NMR (400 MHz, DMSO-d₆) δ=9.47 (br. s, 2H), 7.49(dd, J=1.96, 6.85 Hz, 2H), 7.32-7.39 (m, 3H), 3.23 (t, J=5.62 Hz, 4H),2.30 (dd, J=4.65, 8.56 Hz, 2H), 1.73-1.81 (m, 2H), 1.15-1.25 (m, 1H),0.78-0.86 (m, 2H), 0.28 (s, 6H), 0.05 (s, 6H); MS (ES⁺): m/z=322.10[M+]; LCMS: t_(R)=2.32 min.

Example 15, Example 16, and Example 17

1,1,3,3-Tetramethyl-1,3-bis((pyrimidin-2-yloxy)methyl)disiloxane[Example 15]

A solution of (1,1,3,3-tetramethyldisiloxane-1,3-diyl)dimethanol (1 g,5.14 mmol) and 2-chloropyrimidine (1.17 g, 10.2 mmol) in THF (10 mL) wascharged with sodium (236 mg, 10.2 mmol) at room temperature and heatedto 60° C. for 30 min. The reaction mixture was diluted with diethylether and filtered through a pad of Celite and the filtrate wasconcentrated in vacuo resulting in the crude compound (mixture ofPLF-B-65 and Int-5) which was purified and separated by columnchromatography on silica gel followed by reverse phase Combi flashcolumn chromatography to afford 625 mg, 35% yield, of the title compoundas a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ=8.54-8.59 (m, 4H), 7.08(d, J=1.96 Hz, 2H), 3.97 (d, J=1.47 Hz, 4H), 0.15 (d, J=1.96 Hz, 12H),¹H NMR (400 MHz, CDCl₃) δ=8.50 (d, J=2.45 Hz, 4H), 6.87-6.91 (m, 2H),4.03 (s, 4H), 0.24 (s, 12H); MS (ES⁺): m/z=351.10 [M+H]⁺; LCMS:t_(R)=3.12 min.

(1,1,3,3-Tetramethyldisiloxane-1,3-diyl)dimethanol [Example 17]

A solution of (1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene)diacetate (12 g, 43.1 mmol) in methanol (480 mL) was charged with conc.HCl (1.2 mL) at room temperature and stirred for 24 h. The reactionmixture was stirred with solid sodium bicarbonate and concentrated invacuo and the residue was stirred in ether, filtered. The filtrate wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 0-5% methanol in DCMto afford 7.5 g, 90% yield of the title compound as a colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=3.99-4.05 (m, 2H), 3.01 (s, 4H), 0.00 (s, 12H),¹H NMR (400 MHz, CDCl₃) δ=3.34 (s, 4H), 0.15 (s, 12H); MS (ES⁺):m/z=195.00 [M+]; LCMS: t_(R)=1.60 min.

(1,1,3,3-Tetramethyldisiloxane-1,3-diyl)bis(methylene) diacetate[Example 17]

A solution of acetic acid (6.9 mL, 121.1 mmol) in xylene (140 mL) wascharged with triethyl amine (16.9 mL, 121.1 mmol),1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane (14 g, 60.5 mmol) atroom temperature and heated to 140° C. for 14 h. The reaction mixturewas concentrated in vacuo, diluted with diethyl ether and the solidprecipitated was filtered. The filtrate was concentrated in vacuo,resulting in the crude compound which was purified by columnchromatography on silica gel eluting with 5-15% ethyl acetate inn-hexane to afford 12.6 g, 75% yield, of the title compound as colorlessoil. ¹H NMR (400 MHz, DMSO-d₆) δ=3.60 (s, 4H), 1.94 (s, 6H), 0.06 (s,12H); ¹H NMR (400 MHz, CDCl₃) δ=3.71 (s, 4H), 2.06 (s, 6H), 0.16 (s,12H).

1,3-Bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane (2)

A solution of ice cold pyridine (12.4 mL, 139.7 mmol) and H₂O (1.25 mL,69.8 mmol) in THF (600 mL) was charged withchloro(chloromethyl)dimethylsilane (20 g, 139.7 mmol) dropwise andstirred at room temperature for 1 h. The solid precipitated was filteredand the filtrate was concentrated in vacuo to afford 14.4 g of the titlecompound as colourless oil. The crude compound was used in the next stepwithout further purification or analysis.

Example 19

Benzyl 4-(1,1,3,3-tetramethyl-3-phenyldisiloxanyl)butanoate [Example 19]

A catalytic quantity of Karstedt's catalyst(platinum-divinyltetramethyldisiloxane complex, in xylene, Pt ˜2%, 10mg) was added to a solution of compound 2 (2.1 g, 10 mmol) and benzyl2-(benzyloxycarbonylamino)acrylate (1.7 g, 10 mmol) in dry toluene (5mL). The reaction mixture was stirred for 2 h at 70° C. under nitrogenatmosphere. The solvent was removed under reduced pressure and theresidue was further purified by flash column chromatography on silicagel (hexane:EtOAc=50:1) to afford the desired product (2.7 g, 70.0%yield) as an oil. ¹H NMR (400 MHz, CDCl₃): δ 7.45-7.50 (m, 2H),7.20-7.40 (m, 9H), 5.06 (s, 2H), 2.28 (t, J=7.6 Hz, 2H), 1.60 (m, 2H),0.50 (m, 2H), 0.00 (m, 6H).

Dimethyl(phenyl)silanol (1)

Chlorodimethyl(phenyl)silane (5.0 g, 29 mmol) was added dropwise to arapidly stirred suspension of ammonium carbonate (5.7 g, 59.3 mmol) inether (50 mL) and saturated NaCl aqueous (20 mL) over 5 min at roomtemperature. The reaction mixture was stirred for further 10 min, thenseparated. And the aqueous layer was re-extracted with ether (10 mL×3).The combined organic layers were dried over Na₂SO₄, filtered andconcentrated to afford 1 (4.5 g, ˜100% yield), which was used for nextstep without further purification.

1,1,3,3-tetramethyl-1-phenyldisiloxane (2)

Chlorodimethylsilane (2.8 g, 29 mmol) was added to a stirred solution ofcompound 1 (4.5 g, 29 mmol) and triethylamine (5.9 g, 58 mmol) in DCM(20 mL) at room temperature. The reaction mixture was stirred for 30min. The mixture was washed with saturated NaCl aqueous (10 mL×2). Theorganic layer was dried over anhydrous Na₂SO₄, filtered and concentratedto afford 2 (3.5 g, 57.6% yield), which was used for next step withoutfurther purification.

Example 20

4-(3-(4-(methoxycarbonyl)phenyl)-1,1,3,3-tetramethyldisiloxanyl)butanoicAcid [Example 20]

A solution of HCl-dioxane (5N, 10 mL) was added to a mixture of compound3 (2.6 g, 9 mmol) and 1,3-bis(3-carboxypropyl)tetramethyldisiloxane (3.4g, 11 mmol) in dioxane (5 mL) at room temperature. The reaction mixturewas stirred for 2 h. The solvent was removed under reduced pressure. Theresidue was dissolved in ACN (10 mL), followed by the addition of H₂O(˜0.5 mL). The mixture was stirred for 3 h. The solvent was removed byrotary evaporation. The crude product was purified by columnchromatography on silica gel (hexane:EtOAc=20:1) to afford the desired(3.0 g, 88.3% yield). ¹H NMR (400 MHz, CDCl₃): δ 7.93 (d, J=8.4 Hz, 2H),7.53 (d, J=8.4 Hz, 2H), 3.85 (s, 3H), 2.28 (t, 2H), 1.58 (m, 2H), 0.51(m, 2H), 0.35 (s, 6H), 0.04 (s, 6H). ESI for C₁₆H₂₆O₅Si₂. Found 353.29[M−H]⁻.

Methyl 4-[dimethylsilyloxy(dimethyl)silyl]benzoate (2)

DIEA (2.95 g, 23 mmol) was added to a solution of methyl 4-iodobenzoate(3.0 g, 11 mmol) in dry toluene (15 mL), followed by the addition ofPd(P(tBu)₃)₂ (291 mg, 0.57 mmol) and 1,1,3,3-tetramethyldisiloxane (2.3g, 17 mmol) at 0° C. under nitrogen atmosphere. The reaction mixture wasstirred for 2 h, then quenched with water (20 mL). The organic phase wasseparated and washed with brine (20 mL), dried over anhydrous Na₂SO₄,concentrated to dryness to afford compound 1 (2.6 g, 88.1% yield), whichwas used for next step without further purification.

Example 21

Benzyl4-(3-(3-(((benzyloxy)carbonyl)amino)propyl)-1,1,3,3-tetramethyldisiloxanyl)butanoate[Example 21]

Pt(0) (Karstedt's Catalyst, 15 mg) was added to a mixture of compound 1(1.9 g, 10.0 mmol) and dimethylsilyloxy(dimethyl)silane (1.3 g, 10.0mmol) in toluene (5 mL) at room temperature under nitrogen atmosphere.Benzyl but-3-enoate (1.8 g, 10.0 mmol) was subsequently added to themixture. The reaction mixture was heated to 80° C. and stirred for 2 h.The reaction was judged to be complete by GC-MS analysis, thenconcentrated. The crude product was purified by column chromatography onsilica gel (hexane:EtOAc=40:1) to afford the desired product (1.2 g,64.5% yield). ¹H NMR (300 MHz, CDCl₃): δ 7.33-7.38 (m, 10H), 5.12-5.14(m, 4H), 4.93 (s, 1H), 3.17 (m, 2H), 2.40 (m, 2H), 1.68 (m, 3H), 1.52(m, 2H), 0.95 (d, J=7.5 Hz, 1H), 0.51-0.57 (m, 4H), 0.05-0.13 (m, 12H).ESI for C₂₆H₃₉NO₅Si₂. Found 502.5 [M+H]⁺.

Benzyl allylcarbamate (1)

Cbz-OSu (13.7 g, 58.8 mmol) was added to a suspension of allylamine (2.7g, 54 mmol) and Na₂CO₃ (12.5 g, 118 mmol) in acetonitrile (50 mL) andH₂O (100 mL) at room temperature. The reaction mixture was stirred for 2h, then diluted with H₂O (100 mL). The mixture was extracted with EtOAc(100 mL×3). The combined organic layers were dried over Na₂SO₄,concentrated to afford compound 1 (9.1 g, 88.2% yield).

Example 24

(E) and (Z)-5-(1,1,3,3-Tetramethyl-3-phenyldisiloxanyl)pent-4-enoic Acid[Example 24]

A solution of pent-4-ynoic acid (1 g, 10.19 mmol) in toluene (10 mL) wascharged with 1,1,3,3-tetramethyl-1-phenyldisiloxane (2.14 g, 10.19 mmol)and purged with argon at room temperature for 30 min. To the resultingsolution was added and 2% solution of1,1,3,3-tetramethyl-1-divinyldisiloxane platinum(0) complex in xylene(12.1 mL, 0.51 mmol) and stirred at room temperature for 1 h. Thereaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by column chromatography on silica geleluting with 5-20% ethyl acetate in n-hexane to afford 2.5 g (80%yield), trans-cis isomers of the title compound as a colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=11.97 (br. s, 2H), 7.26-7.49 (m, 10H), 6.02 (d,J=18.59 Hz, 2H), 5.46-5.58 (m, 2H), 2.22 (d, J=15.65 Hz, 8H), 0.20 and0.22 (2s, 12H), 0.01 and 0.03 (2s, 12H), ¹H NMR (400 MHz, CDCl₃) δ7.33-7.59 (m, 10H), 6.09 (d, J=19.07 Hz, 2H), 5.55-5.72 (m, 2H), 2.45(d, J=14.67 Hz, 8H), 0.34 and 0.32 (2s, 12H), 0.15 and 0.13 (2s, 12H);MS (ES⁺): m/z=291.00 [M−18]⁺; LCMS: t_(R)=3.42 min.

Example 26

2,2′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(4,1-phenylene))diaceticAcid [Example 26]

Compound 1 (900 mg, 1.5 mmol) was dissolved in methanol (20 mL) at roomtemperature, followed by the addition of Pd/C (10%, 500 mg). Thereaction was stirred for 5 h under H₂. The mixture was filtered, and thefiltrate was concentrated to dryness to afford the desired product (403mg, 66.8% yield). ¹H NMR (400 MHz, DMSO): δ 7.46 (d, J=8.0 Hz, 4H), 7.25(d, J=8.0 Hz, 4H), 3.56 (s, 4H), 0.30 (s, 12H). ESI for C₂₀H₂₆O₅Si₂.Found 401.47 [M−H]⁻.

Dibenzyl2,2′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(4,1-phenylene))diacetate(1)

Compound benzyl 2-(4-iodophenyl)acetate (1.15 g, 3 mmol) was added to asolution of 1,1,3,3-tetramethyldisiloxane (225 mg, 1.5 mmol) in THF (40mL) under nitrogen atmosphere. Pd(P(t-Bu)₃)₂ (4 mg) was subsequentlyadded to the mixture, followed by the addition of DIEA (800 mg, 6.5mmol). The reaction mixture was stirred at room temperature for 2.5 h.The mixture was concentrated to dryness, and the residue was purified byprep-HPLC to afford 1 (975 mg, 65% yield).

Example 27, Example 28, Example 29, Example 30 and Example 31

4-Methyl-2-(((1,1,3,3,3-pentamethyldisiloxanyl)methyl)thio)pyrimidine[Example 27]

K₂CO₃ (4.3 g, 31 mmol) was added to a solution of4-methylpyrimidine-2-thiol (2.5 g, 15.4 mmol) and 18-crown-6 (0.21 g,0.8 mmol) in toluene (50 mL). The mixture was stirred at 120° C. for 1h. Then chloromethylpentamethyldisiloxane (3.0 g, 15.2 mmol) and NaI(0.12 g, 0.8 mmol) were added. The mixture was stirred at 120° C. foranother 4 h. After cooled to room temperature, the solid was filtered.The filtrate was concentrated to dryness. The residue was purified byflash column chromatography on silica gel (EtOAc/hexane=1:50 to 1:30) toafford the desired product (3.1 g, 68.2% yield). ¹H NMR (400 MHz,CDCl₃): δ 8.24-8.25 (d, J=5.2 Hz, 1H), 6.68-6.70 (d, J=5.2 Hz, 1H), 2.33(s, 3H), 2.31 (s, 2H), 0.10 (s, 6H), 0.00 (s, 9H). ESI forC_(ii)H₂₂N₂OSSi₂. Found 287.63 [M+H]⁺.

2-(((1,1,3,3,3-pentamethyldisiloxanyl)methyl)thio)-4-(trifluoromethyl)pyrimidine[Example 28]

Example 28 (1.6 g, 75.3% yield) was prepared from 4-(trifluoromethyl)pyrimidine-2-thiol following the same procedure for synthesizing Example27. ¹H NMR (400 MHz, CDCl₃): δ 8.62-8.64 (d, J=4.8 Hz, 1H), 7.14-7.15(d, J=4.8 Hz, 1H), 2.34 (s, 2H), 0.10 (s, 6H), 0.00 (s, 9H). ESI forC₁₁H₁₉F₃N₂OSSi₂. Found 341.41 [M+H]⁺.

2-(((1,1,3,3,3-pentamethyldisiloxanyl)methyl)thio)pyrimidine [Example29]

Example 29 (5.6 g, 78.8% yield) was prepared from pyrimidine-2-thiolfollowing the same procedure for compound Example 27. ¹H NMR (400 MHz,CDCl₃): δ 8.42 (s, 1H), 8.41 (s, 1H), 6.83-6.86 (t, 1H), 2.31 (s, 2H),0.10 (s, 6H), 0.00 (s, 9H). ESI for C₁₀H₂₀N₂OSSi₂. Found 273.58 [M+H]⁺.

2-(((1,1,3,3,3-pentamethyldisiloxanyl)methyl)thio)pyridine [Example 30]

Example 30 (1.6 g, 75.6% yield) was prepared from pyridine-2-thiolfollowing the same procedure for compound Example 27. ¹H NMR (400 MHz,CDCl₃): δ 8.31 (m, 1H), 7.34-7.38 (m, 1H), 7.10-7.16 (m, 1H), 6.83-6.87(m, 1H), 2.28 (s, 2H), 0.10 (s, 6H), 0.00 (s, 9H). ESI for C₁₁H₂₁NOSSi₂.Found 272.2 [M+H]⁺.

2-(((1,1,3,3,3-pentamethyldisiloxanyl)methyl)thio)pyrazine [Example 31]

Example 31 (3.5 g, 75.3% yield) was prepared from pyrazine-2-thiolfollowing the same procedure for compound Example 27. ¹H NMR (400 MHz,CDCl₃): δ 8.39-8.40 (d, J=2.4 Hz, 1H), 8.25-8.26 (m, 1H), 8.07-8.08 (d,J=2.4 Hz, 1H), 2.26 (s, 2H), 0.10 (s, 6H), 0.00 (s, 9H). ESI forC₁₀H₂₀N₂OSSi₂. Found 273.65 [M+H]⁺.

Example 32

(E)-2-(2-(1,1,3,3-Tetramethyl-3-vinyldisiloxanyl)vinyl)pyrimidine[Example 32]

A solution of 2-chloropyrimidine (10 g, 87.3 mmol) in DMF (200 mL) wascharged with 1,1,3,3-tetramethyl-1,3-divinyldisiloxane (24.4 g, 131.0mmol), palladium acetate (1.96 g, 8.73 mmol), tri(O-tolyl) phosphine(5.3 g, 17.4 mmol) and solution of sodium acetate (21.4 g, 262.0 mmol)in H₂O (10 mL) at room temperature and heated to 120° C. for 14 h. Thereaction mixture was diluted with H₂O and DCM, the emulsion formed wasfiltered through a pad of Celite. The separated organic layer was washedwith H₂O and dried over anhydrous Na₂SO₄, filtered and concentrated invacuo resulting in the crude compound which was purified by columnchromatography on silica gel followed by combiflash columnchromatography to afford 3.40 g, 15% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.80 (d, J=4.89 Hz, 2H), 7.38(t, J=4.89 Hz, 1H), 7.30 (d, J=19.07 Hz, 1H), 6.98 (d, J=18.59 Hz, 1H),6.10-6.17 (m, 1H), 5.97 (dd, J=3.91, 14.67 Hz, 1H), 5.73-5.81 (m, 1H),0.24 (s, 6H), 0.16 (s, 6H), ¹H NMR (400 MHz, CDCl₃) δ=8.60-8.77 (m, 2H),7.38 (d, J=19.07 Hz, 1H), 7.12 (d, J=8.80 Hz, 2H), 6.09-6.22 (m, 1H),5.95 (d, J=14.18 Hz, 1H), 5.71-5.79 (m, 1H), 0.26 (s, 6H), 0.18 (s, 6H);MS (ES⁺): m/z=265.07 [M+H]⁺; LCMS: t_(R)=3.72 min.

Example 33 and Example 34

N-(3-(1,1,3,3-Tetramethyl-3-((pyrimidin-2-ylthio)methyl)disiloxanyl)propyl)isobutyramide [Example 34]

A solution of pyrimidine-2-thiol (91 mg, 0.81 mmol) in acetonitrile (10mL) was charged with potassium carbonate (111 mg, 0.81 mmol) andN-(3-(3-(chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)isobutyramide(250 mg, 0.81 mmol) at room temperature and was further heated to 50° C.for 3 h. The reaction mixture was concentrated in vacuo resulting in thecrude compound which was purified by column chromatography on silica geleluting with 20-40% ethyl acetate in n-hexane to afford 280 mg, 90%yield, of as colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.57 (d, J=4.89Hz, 2H), 7.62 (br. s, 1H), 7.14 (t, J=4.89 Hz, 1H), 2.89-2.97 (m, 2H),2.32 (s, 2H), 2.20-2.29 (m, 1H), 1.33 (td, J=7.70, 15.90 Hz, 2H), 0.92(d, J=6.85 Hz, 6H), 0.39-0.47 (m, 2H), 0.11 (s, 6H), 0.050 (s, 6H).

¹H NMR (400 MHz, CDCl₃) δ=8.51 (d, J=3.91 Hz, 2H), 6.95 (br. s, 1H),3.22 (d, J=6.36 Hz, 2H), 2.42 (s, 2H), 2.27-2.37 (m, 1H), 1.54 (d,J=7.34 Hz, 2H), 1.15 (d, J=6.36 Hz, 6H), 0.50-0.58 (m, 2H), 0.21 (s,6H), 0.09 (s, 6H); MS (ES⁺): m/z=385.85 [M+H]⁺; LCMS: t_(R)=3.43 min.

N-(3-(3-(Chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)isobutyramide(4)

A solution of N-(3-(chlorodimethylsilyl)propyl)isobutyramide (569 mg,2.57 mmol) in acetonitrile (10 mL) was charged with(chloromethyl)dimethylsilanol (319 mg, 2.57 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuo,dissolved in diethyl ether and concentrated resulting in the crudecompound which was purified by column chromatography on silica geleluting with 10-40% ethyl acetate in n-hexane to afford 557 mg, 70%yield, of the title compound as a colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=7.62 (br. s, 1H), 2.88-2.96 (m, 2H), 2.78 (s, 2H), 2.21-2.29(m, 1H), 1.27-1.36 (m, 2H), 0.91 (d, J=6.85 Hz, 6H), 0.39-0.46 (m, 2H),0.09 (s, 6H), 0.00 (s, 6H).

N-(3-(Chlorodimethylsilyl)propyl)isobutyramide (3)

A solution ofN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2-methylpropanamide)(1 g, 2.57 mmol) in dioxane: HCl (4M, 10 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in 569 mg of the title compound as a colorless oil. The crudecompound was used in the next step without further purification andanalysis.

N,N′-((1,1,3,3-Tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2-methylpropanamide)[Example 33]

A solution of3,3′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (1 g,4.03 mmol) in DCM (10 mL) at 0° C. was charged with triethyl amine (1.4mL, 10.0 mmol) and isobutyryl chloride (0.92 mL, 8.80 mmol) and stirredat room temperature for 1 h. The solid precipitated was filtered, washedwith diethyl ether and the filtrate was concentrated in vacuo resultingin the crude compound which was purified by column chromatography onsilica gel eluting with 10-40% ethyl acetate in n-hexane to afford 1.25g, 80% yield, of the title compound as a white solid. ¹H NMR (400 MHz,DMSO-d₆) δ=7.66 (br. s, 2H), 2.95 (d, J=6.36 Hz, 4H), 2.29 (t, J=6.60Hz, 2H), 1.31-1.40 (m, 4H), 0.95 (d, J=6.85 Hz, 12H), 0.38-0.47 (m, 4H),0.00 (s, 12H); MS-ELSD (ES⁺): m/z=411.00 [M+Na]⁺; LCMS: t_(R)=2.72 min.

Example 35

N-Methyl-4-(1,1,3,3-tetramethyl-3-((pyrimidin-2-ylthio)methyl)disiloxanyl)butanamide[Example 35]

A solution of4-(3-(chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)-N-methylbutanamide(200 mg, 0.71 mmol) in acetonitrile (10 mL) was charged with potassiumcarbonate (147 mg, 1.06 mmol) and pyrimidine-2-thiol (79 mg, 0.71 mmol)at room temperature and heated to 50° C. for 2 h. The reaction mixturewas concentrated in vacuo, diluted with ethyl acetate and stirred for 15min. The solid was filtered and the filtrate was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 40-50% ethyl acetate inn-hexane to afford 58 mg, 23% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.57 (d, J=4.89 Hz, 2H), 7.61(br. s, 1H), 7.14 (t, J=4.89 Hz, 1H), 2.49 (d, J=4.40 Hz, 2H), 2.33 (s,2H), 1.99 (t, J=7.34 Hz, 2H), 1.41-1.50 (m, 3H), 0.39-0.46 (m, 2H), 0.11(s, 6H), 0.00 (s, 6H); MS (ESMS): m/z=380.00 [M+Na]⁺.

4-(3-(Chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)-N-methylbutanamide(5)

A solution of4-(3-(3-chloropropyl)-1,1,3,3-tetramethyldisiloxanyl)-N-methylbutanamide(450 mg, 1.45 mmol) in dioxane: HCl (4M, 10 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude chloro intermediate which was used furtherwithout purification. The crude intermediate was dissolved inacetonitrile (10 mL) followed by addition of DIPEA (0.5 mL, 2.91 mmol)and (chloromethyl)dimethylsilanol (361 mg, 2.91 mmol) and stirred atroom temperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 30-60% ethyl acetate inn-hexane to afford 204 mg, 50% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=7.66 (br. s, 1H), 2.54 (d,J=4.40 Hz, 3H), 2.05 (t, J=7.34 Hz, 2H), 1.66-1.76 (m, 1H), 1.46-1.56(m, 2H), 0.56-0.63 (m, 1H), 0.43-0.51 (m, 2H), 0.15 (s, 3H), 0.06 (s,6H), 0.04 (s, 3H).

4-(3-(3-Chloropropyl)-1,1,3,3-tetramethyldisiloxanyl)-N-methylbutanamide(3)

A solution of4-(3-(3-chloropropyl)-1,1,3,3-tetramethyldisiloxanyl)butanoic acid (750mg, 2.53 mmol) in dichloromethane (10 mL) was charged with potassiumcarbonate (699 mg, 5.06 mmol), HATU (1.24 g, 3.29 mmol), 2M solution ofmethyl amine in THF (2.5 mL, 5.06 mmol) and stirred at room temperaturefor 3 h. The reaction mixture was concentrated in vacuo resulting in thecrude compound which was purified by column chromatography on silica geleluting with 30-60% ethyl acetate in n-hexane to afford 469 mg, 60%yield, of the title compound as a colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=7.62 (br. s, 1H), 3.56 (t, J=5.96 Hz, 2H), 2.51 (br. s, 3H),2.01 (t, J=6.68 Hz, 2H), 1.68 (d, J=6.68 Hz, 2H), 1.47 (d, J=6.68 Hz,2H), 0.57 (d, J=8.11 Hz, 2H), 0.43 (d, J=7.63 Hz, 2H), 0.01 (br. s,12H).

4-(3-(3-Chloropropyl)-1,1,3,3-tetramethyldisiloxanyl)butanoic Acid (2)

A solution of magnesium (183 mg, 7.65 mmol) in THF (10 mL) was added apinch of iodine and1,3-bis(3-chloropropyl)-1,1,3,3-tetramethyldisiloxane (1 g, 3.48 mmol)dropwise at room temperature and further heated to 60° C. for 2 h. Theresulting solution was slowly cooled to −78° C. and charged with dryice. The reaction mixture was warmed to room temperature and quenchedwith dilute hydrochloric acid solution and extracted with ethyl acetate(3×25 mL). The combined organic layers were dried over anhydrous Na₂SO₄,filtered and concentrated in vacuo resulting in the crude compound whichwas purified by column chromatography on silica gel eluting with 40-50%ethyl acetate in n-hexane to afford 772 mg, 75% yield, of the titlecompound as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=11.95 (br. s,1H), 3.52-3.66 (m, 3H), 2.21 (t, J=6.44 Hz, 2H), 1.53 (d, J=6.68 Hz,2H), 0.47-0.63 (m, 5H), 0.04 (br. s, 12H).

Example 36

N-(3-(1,1,3,3-Tetramethyl-3-((pyrimidin-2-ylthio)methyl)disiloxanyl)propyl)benzenesulfonamide [Example 36]

A solution ofN-(3-(3-(chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)benzenesulfonamide (600 mg, 1.57 mmol) in acetonitrile (10 mL) wascharged with potassium carbonate (326 mg, 2.36 mmol) andpyrimidine-2-thiol (177 mg, 1.57 mmol) at room temperature and heated to50° C. for 3 h. The reaction mixture was concentrated in vacuo, dilutedwith ethyl acetate and stirred for 15 min. The solid precipitated wasfiltered and the filtrate was concentrated in vacuo resulting in thecrude compound which was purified by column chromatography on silica geleluting with 20-40% ethyl acetate in n-hexane to afford 359 mg, 50%yield, of the title compound as a colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=8.63 (d, J=4.89 Hz, 2H), 7.79 (d, J=6.85 Hz, 2H), 7.55-7.66(m, 4H), 7.20 (t, J=4.89 Hz, 1H), 2.67-2.75 (m, 2H), 2.36 (s, 2H), 1.36(td, J=7.83, 15.65 Hz, 2H), 0.38-0.48 (m, 2H), 0.14 (s, 6H), 0.00 (s,6H); MS (ELSD): m/z=411.00[M+Na]⁺; LCMS: t_(R)=2.72 min.

N-(3-(3-(Chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)benzenesulfonamide(4)

A solution of N-(3-(hydroxydimethylsilyl)propyl)benzenesulfonamide (600mg, 2.19 mmol) in acetonitrile (10 mL) was charged withchloro(chloromethyl)dimethylsilane (312 mg, 2.19 mmol) and stirred atroom temperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 15-25% ethyl acetate inn-hexane to afford 626 mg, 75% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=7.78 (d, J=6.20 Hz, 2H), 7.60(d, J=6.20 Hz, 4H), 2.81 (br. s, 2H), 2.71 (d, J=5.72 Hz, 2H), 1.35 (br.s, 2H), 0.43 (d, J=7.15 Hz, 2H), 0.11 (br. s, 6H), 0.00 (br. s, 6H).

N-(3-(Hydroxydimethylsilyl)propyl)benzenesulfonamide (3)

A solution ofN,N-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dibenzenesulfonamide (1 g, 1.89 mmol) in 4M HCl in dioxane (10 mL) wasstirred at room temperature for 30 min. The reaction mixture wasconcentrated in vacuo resulting in the crude chloro intermediate whichwas used in further without purification. To the crude intermediate wasadded aqueous sodium bicarbonate solution (20 mL) and stirred at roomtemperature for 30 min. The reaction mixture was extracted with ethylacetate (3×25 mL) and the combined organic layers were dried overanhydrous Na₂SO₄, filtered and concentrated in vacuo resulting in thecrude compound which was purified by column chromatography on silica geleluting with 20-40% ethyl acetate in n-hexane to afford 672 mg, 65%yield, of the title compound as a colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=7.85 (d, J=6.68 Hz, 2H), 7.67 (d, J=7.15 Hz, 4H), 5.36 (br.s, 1H), 2.77 (d, J=6.20 Hz, 2H), 1.43 (br. s, 2H), 0.45 (d, J=7.15 Hz,2H), 0.00 (br. s, 6H).

N,N′-((1,1,3,3-Tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dibenzenesulfonamide (2)

A solution of 33,3′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (1 g,4.03 mmol) in dichloromethane (50 mL) at 0° C. was charged with triethylamine (1.4 mL, 10.08 mmol) and benzenesulfonyl chloride (1.56 g, 8.87mmol) and stirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo, diluted with diethyl ether and stirred for 15min. The solid was filtered and the filtrate was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 15-25% ethyl acetate inn-hexane to afford 1.89 g, 89% yield, of the title compound as a whitesolid. ¹H NMR (400 MHz, DMSO-d₆) δ=7.85 (d, J=7.34 Hz, 4H), 7.62-7.72(m, 8H), 2.76 (q, J=6.68 Hz, 4H), 1.38 (td, J=7.83, 15.65 Hz, 4H),0.39-0.47 (m, 4H), 0.00 (s, 12H).

Example 37, Example 38, Example 39, and Example 40

1,3-Bis(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane[Example 40]

A solution of1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(1 g, 3.267 mmol) in ethanol (50 mL) was added sodium azide (1.84 g,6.535 mmol) and heated to reflux for 2 h. The reaction mixture wasconcentrated in vacuo resulting in crude residue which was stirred indiethyl ether. The suspension was filtered and the filtrate wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica get eluting with ethyl acetate inn-hexane to afford 1.1 g, 90% yield, of the title compound as an offwhite solid. ¹H NMR (400 MHz, DMSO-d₆) δ=8.65 (s, 4H), 4.49 (s, 4H),2.41 (s, 4H), 0.18 (s, 12H); MS (ES⁺): m/z=256.00/256.05 monomer [M+H]⁺;LCMS: t_(R)=2.54/3.74 min.

1,3-Bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane[Example 39]

A solution of((((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene))bis(sulfanediyl))bis(pyrimidine-2,5-diyl))dimethanol(15 g, 33.93 mmol) in DCM (200 mL) was cooled to 0° C. and charged withDIPEA (17.7 mL, 101.8 mmol) and tosyl chloride (14.2 g, 67.87 mmol)under a nitrogen atmosphere and stirred at room temperature for 5 h. Thereaction mixture was concentrated in vacuo resulting in crude compoundwhich was purified by column chromatography on silica gel eluting with30-70% ethyl acetate in n-hexane to afford 8.12 g, 50% yield, of thetitle compound as an off white solid. ¹H NMR (400 MHz, DMSO-d₆) δ=8.69(s, 4H), 4.77 (s, 4H), 2.41 (s, 4H), 0.18 (s, 12H); MS (ES⁺): m/z=248.95monomer [M+H]⁺, 231.00 monomer [M−18]⁺; LCMS: t_(R)=2.62/3.82 min.

((((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene))bis(sulfanediyl))bis(pyrimidine-2,5-diyl))dimethanol[Example 38]

A solution of2,2′-(((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene))bis(sulfanediyl)) bis(pyrimidine-5-carbaldehyde) (22 g, 50.22 mmol) inethanol (150 mL) was cooled to 0° C. and charged with sodium borohydride(1.89 g, 50.22 mmol) then stirred at room temperature for 1 h. Thereaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by silica gel column chromatography onsilica gel eluting with 40-100% ethyl acetate to afford 15.54, 70%yield, of the title compound as a white solid. ¹H NMR (400 MHz, DMSO-d₆)δ=8.54 (s, 4H), 5.34 (t, J=5.55 Hz, 2H), 4.46 (d, J=5.31 Hz, 4H), 2.40(s, 4H), 0.18 (s, 12H); MS (ES⁺): m/z=443.20 [M+H]⁺/465.25 [M+Na]⁺;LCMS: t_(R)=1.99/2.81 min.

2,2′-(((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene))bis(sulfanediyl))bis(pyrimidine-5-carbaldehyde) [Example 37]

A solution of 2-mercaptopyrimidine-5-carbaldehyde (34.5 g, 246.4 mmol)in acetonitrile (100 mL) was added potassium carbonate (102 g, 739.2mmol) and (chloromethyl)(ethoxy)dimethylsilane (37.6 g, 246.4 mmol) andstirred at 60° C. for 1 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by columnchromatography on silica gel eluting with 20-50% ethyl acetate inn-hexane to afford 22.11 g, 35% yield of the title compound as an offwhite solid. ¹H NMR (400 MHz, DMSO-d₆) δ=9.93 (s, 2H), 8.94 (s, 4H),2.43 (s, 4H), 0.14 (s, 12H); MS (ES⁺): m/z=229.00 monomer [M+H]⁺; LCMS:t_(R)=3.52 min.

Int-4 Aldehyde

In-4 aldehyde (2-mercaptopyrimidine-5-carbaldehyde) was preparedaccording to a literature preparation: Organic Letters 2014, 16,1282-1285, 2014. ¹H NMR (400 MHz, DMSO-d₆) δ=14.33 (br. s, 1H), 9.76 (s,1H), 8.70 (br. s, 2H), 3.33 (br. s, 1H).

Example 41 and Example 42

5-(N-(3-(3-(((5-(Chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate[Example 42]

A solution of3-(3-(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine(40 mg, 0.109 mmol) in DCM (5 mL) was added DIPEA (28 mg, 0.20 mmol) and5-(chlorosulfonyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(63 mg, 0.101 mmol) at room temperature and stirred for 1 h. Thecompletion of reaction was monitored by LCMS. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby silica gel column chromatography eluting with 0-10% methanol in DCMto afford 29 mg, 30% yield, of the title compound as violet solid. ¹HNMR (400 MHz, DMSO-d₆) δ=8.65 (s, 2H), 8.37-8.38 (m, 1H), 7.87-7.91 (m,2H), 7.42 (d, J=7.83 Hz, 1H), 6.94-6.98 (m, 3H), 6.90 (d, J=1.47 Hz,2H), 4.73 (s, 2H), 3.55-3.67 (m, 8H), 2.75-2.83 (m, 1H), 2.36 (s, 2H),1.44 (td, J=7.70, 15.90 Hz, 2H), 1.14-1.21 (m, 12H), 0.77-0.84 (m, 2H),0.43-0.51 (m, 2H), 0.11-0.15 (m, 6H), 0.01-0.04 (m, 6H); MS (ES⁺):m/z=904.55 [M+H]⁺; LCMS: t_(R)=3.66 min.

3-(3-(((5-(Chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine[Example 41]

A solution of1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(1 g, 2.0 mmol) in 4M HCl in dioxane (20 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude reaction mixture. The crude was dissolved inacetonitrile (50 mL) and followed by addition of 75 mg and sodium(3-aminopropyl) dimethylsilanolate (638 mg, 2.0 mmol) and stirred atroom temperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 0-10% methanol in DCM toafford 500 mg, 35% yield, of the title compound as colourless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=8.69 (s, 1H), 7.77 (br. s, 1H), 4.76 (s, 2H),3.34 (br. s, 2H), 2.89-3.03 (m, 2H), 2.66-2.79 (m, 1H), 2.40 (d, J=3.91Hz, 1H), 1.47-1.61 (m, 1H), 0.92-1.00 (m, 2H), 0.48-0.56 (m, 1H), 0.17(d, J=2.45 Hz, 6H), 0.07 (d, J=4.89 Hz, 6H); MS (ES+): m/z=364.10[M+H]⁺;LCMS: t_(R)=2.20 min.

Example 43

N-(3-(3-(((5-(Azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl) acetamide [Example 43]

A solution ofN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(400 mg, 1.2 mmol) and1,3-bis(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(592 mg, 1.2 mmol) in 4M HCl in dioxane (10 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude mixture of2-((3-(chlorodimethylsilyl)propyl)amino)-2-oxoethan-1-ylium (4) and5-(azidomethyl)-2-(((chlorodimethylsilyl)methyl)thio)pyrimidine (5). Thecrude mixture was dissolved in acetonitrile (10 mL) and charged withwater (43 mg, 2.4 mmol) followed by DIPEA (2.46 g, 7.2 mmol) and stirredat room temperature for 1 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by columnchromatography on silica gel eluting with 40-70% ethyl acetate inn-hexane to afford 280 mg, 73% yield, of the title compound as acolourless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.65 (s, 2H), 7.78 (br. s,1H), 4.48 (s, 2H), 2.91-3.00 (m, 2H), 2.38 (s, 2H), 1.75 (s, 3H),1.32-1.41 (m, 2H), 0.42-0.49 (m, 2H), 0.15 (s, 6H), 0.03 (s, 6H); MS(ES⁺): m/z=413.09 [M+H]⁺; LCMS: t_(R)=3.26 min.

Example 44 and Example 45

3-(3-(((5-(Azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine [Example 44]

A solution of(9H-fluoren-9-yl)methyl(3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate(3.4 g, 5.734 mmol) was charged with ethanolic ammonia (40 mL) andstirred at room temperature for 15 h. The reaction mixture wasconcentrated in vacuo and the crude compound was purified by combiflashcolumn chromatography eluting with 0-10% methanol saturated with ammoniain DCM to afford 1.10 g, 52% yield, of the title compound as a lightbrown oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.67 (s, 2H), 4.51 (s, 2H),2.45-2.52 (m, 4H), 2.39-2.43 (m, 2H), 1.31-1.41 (m, 2H), 0.46-0.53 (m,2H), 0.18 (s, 6H), 0.06 (s, 6H); MS (ES⁺): m/z=371.20 [M+H]⁺; LCMS:t_(R)=2.23 min.

(9H-fluoren-9-yl)methyl(3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate[Example 45]

A solution of mixture1,3-bis(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3tetramethyldisiloxane(2.50 g, 3.45 mmol) and bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(1.7 g, 3.45 mmol) were dissolved in 4M HCl in dioxane (30 mL) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude mixture of 4 and 5. Themixture of 4 and 5 was dissolved in acetonitrile (30 mL) then chargedwith water (124 mg, 6.91 mmol), DIPEA (2.6 g, 20.7 mmol) and stirred atroom temperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 10-25% ethyl acetate inn-hexane to afford 3.40 g, 85% yield of the title compound as acolourless oil. ¹H NMR (400 MHz, CDCl₃) δ=8.50 (s, 2H), 7.78-7.83 (m,2H), 7.64 (d, J=7.34 Hz, 2H), 7.41-7.47 (m, 2H), 7.32-7.38 (m, 2H), 4.44(d, J=6.85 Hz, 2H), 4.34 (s, 2H), 4.23-4.30 (m, 1H), 3.18-3.26 (m, 2H),2.47 (s, 2H), 1.53-1.61 (m, 1H), 1.28-1.33 (m, 2H), 0.55-0.63 (m, 2H),0.27 (s, 6H), 0.15 (s, 6H), MS (ES⁺): m/z=593.35 [M+H]⁺; LCMS:t_(R)=4.03 min.

Bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(3)

A solution of3,3′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (3 g,12 mmol) in DCM (60 mL) was charged with DIPEA (4.68 g, 36 mmol) andFmoc-Cl (6.8 g, 26.6 mmol) and stirred at room temperature for 1 h. Thereaction mixture was diluted with water and separated organic layer wasdried over sodium sulphate. The organic layer was diluted with 10%methanol in DCM and concentrated in vacuo resulting in the crudecompound. The crude compound was stirred in methanol, filtered and driedto afford 7.96 g, 95% yield of the title compound as a white solid. ¹HNMR (400 MHz, DMSO-d₆) δ=7.89 (d, J=7.34 Hz, 4H), 7.68 (d, J=7.34 Hz,4H), 7.38-7.44 (m, 4H), 7.32 (t, J=7.34 Hz, 4H), 4.29 (d, J=6.85 Hz,4H), 4.21 (d, J=6.36 Hz, 2H), 4.04 (q, J=7.17 Hz, 2H), 2.95 (q, J=6.52Hz, 4H), 1.41 (td, J=7.58, 15.16 Hz, 4H), 0.43-0.50 (m, 4H), 0.04 (s,12H).

Example 46, Example 47, Example 48, and Example 49

5-(N-(2-(4-(3-(((5-((3-(((3S,8S,11S,14R)-1-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)phenyl)-3,14-dicarboxy-8-(carboxymethyl)-11-((3-(5,5-difluoro-7-methyl-5H-514,614-dipyrrolo[1,2-c:2′,1′-f][1,3,2]diazaborinin-3-yl)propanamido)methyl)-1,6,9,12-tetraoxo-2,7,10,13-tetraazapentadecan-15-yl)thio)-2,5-dioxopyrrolidin-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanamido)ethyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate[Example 46]

A solution of5-(N-(2-(4-(3-(((5-((3-(((3S,8S,11S,14R)-1-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)phenyl)-11-(aminomethyl)-3,14-dicarboxy-8-(carboxymethyl)-1,6,9,12-tetraoxo-2,7,10,13-tetraazapentadecan-15-yl)thio)-2,5-dioxopyrrolidin-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanamido)ethyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(68.8 mg, 0.0386 mmol) was charged 2,5-dioxopyrrolidin-1-yldifluoro-7-methyl-5H-514,614-dipyrrolo[1,2-c:2′,1′-f][1,3,2]diazaborinin-3-yl)propanoate(18 mg, 0.0463 mmol) at room temperature and stirred for 2 h. Thereaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by trituration in ethyl acetate to afford 30mg, 38% yield of the title compound as a violet solid. ¹H NMR (400 MHz,DMSO-d₆) δ=8.64 (br. s, 2H), 8.51 (br. s, 1H), 8.41 (br. s, 1H),8.05-8.22 (m, 4H), 7.94 (d, J=8.31 Hz, 2H), 7.60-7.68 (m, 2H), 7.48 (d,J=7.83 Hz, 1H), 7.03 (d, J=8.80 Hz, 2H), 6.90-7.01 (m, 4H), 6.62 (d,J=7.83 Hz, 2H), 6.26-6.34 (m, 2H), 5.43 (br. s, 2H), 4.60 (br. s, 2H),4.44-4.56 (m, 5H), 4.26 (br. s, 4H), 4.13 (br. s, 2H), 4.04 (d, J=7.34Hz, 5H), 3.48-3.70 (m, 16H), 3.16 (d, J=8.80 Hz, 3H), 2.84-3.12 (m,11H), 2.68 (br. s, 3H), 2.29-2.35 (m, 2H), 2.25 (br. s, 2H), 1.98-2.10(m, 4H), 1.51 (br. s, 3H), 1.17-1.28 (m, 8H), 0.85 (d, J=6.36 Hz, 2H),0.46 (d, J=8.31 Hz, 2H), 0.14 (s, 6H), 0.04 (s, 6H), MS (ES⁺): m/z=1028[M/2+H]⁺; LCMS: t_(R)=2.97 min.

5-(N-(2-(4-(3-(((5-((3-(((3S,8S,11S,14R)-1-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)phenyl)-11-(aminomethyl)-3,14-dicarboxy-8-(carboxymethyl)-1,6,9,12-tetraoxo-2,7,10,13-tetraazapentadecan-15-yl)thio)-2,5-dioxopyrrolidin-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanamido)ethyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(10)

A solution of2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)-5-(N-(2-(4-(3-(((5-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanamido)ethyl)sulfamoyl)benzenesulfonate(40 mg, 0.0386 mmol) in DMF (1.5 mL) was charged with DIPEA (0.02 mL,0.115 mmol) andN5-((S)-1-(((S)-3-amino-1-(((R)-1-carboxy-2-mercaptoethyl)amino)-1-oxopropan-2-yl)amino)-3-carboxy-1-oxopropan-2-yl)-N2-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzoyl)-L-glutamine(28.6 mg, 0.0385 mmol) and stirred at room temperature for 1 h. Thecrude reaction mixture was used directly in the next step withoutwork-up or further purification. MS (ES⁺): m/z=891.48 [M/2+H]⁺; LCMS:t_(R)=2.39 min.

2-(6-(Diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)-5-(N-(2-(4-(3-(((5-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanamido)ethyl)sulfamoyl)benzenesulfonate [Example 47]

A solution of 2,5-dioxopyrrolidin-1-yl4-(3-(((5-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanoate(100 mg, 0.181 mmol) in DMF (2 mL) was charged with DIPEA (0.09 mL,0.545 mmol) and5-(N-(2-ammonioethyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonatechloride (110 mg, 0.181 mmol) and stirred at room temperature for 4 h.The reaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by column chromatography on silica geleluting with 0-10% methanol in DCM to afford 100 mg, 53% yield, of thetitle compound as violet solid. ¹H NMR (400 MHz, DMSO-d₆) δ=8.49 (s,2H), 8.38 (d, J=1.47 Hz, 1H), 7.98 (t, J=5.62 Hz, 1H), 7.89 (dd, J=1.47,7.83 Hz, 1H), 7.83 (t, J=5.62 Hz, 1H), 7.44 (d, J=8.31 Hz, 1H),6.94-7.04 (m, 6H), 6.91 (d, J=1.96 Hz, 2H), 4.55 (s, 2H), 3.56-3.67 (m,8H), 3.07-3.14 (m, 3H), 2.82-2.91 (m, 3H), 2.57 (s, 2H), 2.27-2.34 (m,3H), 2.03 (t, J=7.34 Hz, 3H), 1.47 (td, J=7.70, 15.90 Hz, 3H), 1.20-1.24(m, 2H), 0.78-0.86 (m, 2H), 0.40-0.49 (m, 3H), 0.11 (s, 6H), −0.02 (s,6H); MS (ES⁺): m/z=1037.15 [M+H]⁺; LCMS: t_(R)=3.29 min.

2,5-Dioxopyrrolidin-1-yl4-(3-(((5-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanoate[Example 49]

A solution of4-(3-(((5-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanoicacid (270 mg, 0.597 mmol) in DCM (5 mL) was charged with DCC (135 mg,0.657 mmol) and N-hydroxysuccinimide (75 mg, 0.657 mmol) and stirred atroom temperature for 15 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by columnchromatography on silica gel eluting with 0-5% methanol in DCM to afford222 mg, 68% yield, of the title compound as a colourless oil. ¹H NMR(400 MHz, DMSO-d₆) δ=8.50 (s, 2H), 7.03 (s, 2H), 4.55 (s, 2H), 2.78 (s,4H), 2.60-2.66 (m, 2H), 2.35 (s, 2H), 1.59-1.68 (m, 2H), 0.56-0.62 (m,2H), 0.14 (s, 6H), 0.03 (s, 6H); MS (ES⁺): m/z=550.80 [M+H]⁺; LCMS:t_(R)=3.39 min.

4-(3-(((5-((2,5-Dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanoicAcid [Example 48]

A solution of1,1′-(((((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene))bis(sulfanediyl))bis(pyrimidine-2,5-diyl))bis(methylene))bis(1H-pyrrole-2,5-dione)(400 mg, 0.666 mmol) and4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)dibutyric acid (203 mg,0.666 mmol) was charged with 4M HCl in dioxane (10 mL) and stirred atroom temperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate. The crude intermediate wasdissolved in acetonitrile (20 mL) and followed by addition of DIPEA(0.69 mL, 3.999 mmol) and water (20 mL) and stirred for 1 h at roomtemperature. The reaction mixture was concentrated in vacuo resulting inthe crude compound which was purified by column chromatography on silicagel eluting with 0-5% methanol in DCM to afford 270 mg, 90% yield, ofthe title compound as a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ=11.93(s, 1H), 8.53 (s, 2H), 7.06 (s, 2H), 4.58 (s, 2H), 2.37 (s, 2H), 2.20(t, J=7.09 Hz, 2H), 1.47-1.59 (m, 2H), 0.47-0.56 (m, 2H), 0.17 (s, 6H),0.05 (s, 6H); MS (ES⁺): m/z=454.18 [M+H]⁺; LCMS: t_(R)=3.26 min.

5-(N-(2-Ammonioethyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonateChloride (4)

A solution of5-(N-(2-((tert-butoxycarbonyl)amino)ethyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(170 mg, 0.242 mmol) in 6N aqueous HCl (4 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuo toafford 116 mg, 80% yield, of the title compound as dark red solid. ¹HNMR (400 MHz, DMSO-d₆) δ=8.45 (d, J=1.47 Hz, 1H), 8.26 (t, J=5.62 Hz,1H), 7.96-7.99 (m, 1H), 7.92 (br. s, 2H), 7.53 (d, J=7.83 Hz, 1H),7.01-7.06 (m, 2H), 6.94-6.99 (m, 3H), 4.00-4.07 (m, 1H), 3.59-3.72 (m,7H), 3.39 (s, 2H), 3.06-3.13 (m, 2H), 2.95 (d, J=5.38 Hz, 2H), 1.15-1.26(m, 12H); MS (ES⁺): m/z=601.40 [M+H]⁺; LCMS: t_(R)=1.99 min.

5-(N-(2-((tert-butoxycarbonyl)amino)ethyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(3)

A solution of5-(chlorosulfonyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(170 mg, 0.242 mmol) in DMF (4 mL) was charged with DIPEA (0.18 mL, 1.03mmol) and tert-butyl(2-aminoethyl)carbamate (55.4 mg, 0.346 mmol) wasstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 0-5% methanol in DCMto afford 179 mg, 74% yield, of the title compound as pink solid. ¹H NMR(400 MHz, DMSO-d₆) δ=8.41 (s, 1H), 8.02 (t, J=5.87 Hz, 1H), 7.93 (d,J=7.83 Hz, 1H), 7.48 (d, J=7.83 Hz, 1H), 6.97-7.06 (m, 4H), 6.94 (s,2H), 6.87 (br. s, 1H), 3.58-3.70 (m, 8H), 2.99-3.06 (m, 2H), 2.85-2.91(m, 2H), 1.37 (s, 9H), 1.21 (t, J=6.85 Hz, 12H); MS (ES⁺): m/z=701.35[M+H]⁺; LCMS: t_(R)=2.92 min.

Example 50

3-(1,1,3,3-Tetramethyl-3-(((5-(prop-2-yn-1-yl)pyrimidin-2-yl)thio)methyl)disiloxanyl)propan-1-amine[Example 50]

A solution of(9H-fluoren-9-yl)methyl(3-(1,1,3,3-tetramethyl-3-(((5-(prop-2-yn-1-yl)pyrimidin-2-yl)thio)methyl)disiloxanyl)propyl)carbamate(2.50 g, 4.347 mmol) in saturated ethanolic ammonia (50 mL) was stirredat room temperature for 15 h. The reaction mixture was concentrated invacuo and the crude compound was purified by combiflash columnchromatography eluting with 0-10% methanol saturated with ammonia in DCMto afford 250 mg, 16% yield, of the title compound as colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=8.52 (s, 2H), 6.36 (t, J=6.85 Hz, 1H), 5.39 (d,J=6.85 Hz, 2H), 2.46 (d, J=6.85 Hz, 2H), 2.38 (s, 2H), 1.66 (br. s, 2H),1.29-1.38 (m, 2H), 0.44-0.51 (m, 2H), 0.16 (s, 6H), 0.05 (s, 6H); MS(ES⁺): m/z=354.15 [M+H]⁺; LCMS: t_(R)=2.33 min.

(9H-fluoren-9-yl)methyl(3-(1,1,3,3-tetramethyl-3-(((5-(prop-2-yn-1-yl)pyrimidin-2-yl)thio)methyl)disiloxanyl)propyl)carbamate(6)

A solution of mixture of1,1,3,3-tetramethyl-1,3-bis(((5-(prop-2-yn-1-yl)pyrimidin-2-yl)thio)methyl)disiloxane(2.48 g, 5.050 mmol) and bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(3.50 g, 5.05 mmol) in 4M HCl in dioxane (35 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 4 and 5. The mixture of 4 and 5 wasdissolved in acetonitrile (350 mL) and followed by addition of water(0.90 mL, 5.05 mmol) and DIPEA (2.63 mL, 15.15 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by chromatography onsilica gel eluting with 0-40% ethyl acetate in n-hexane to afford 2.50g, 86% yield, of the title compound as a colorless oil. MS (ES⁺):m/z=576.45 [M+H]⁺; LCMS: t_(R)=3.98 min.

1,1,3,3-Tetramethyl-1,3-bis(((5-(prop-2-yn-1-yl)pyrimidin-2-yl)thio)methyl)disiloxane(2)

A solution of1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(6 g, 12.52 mmol) in THF (200 mL) was added copper iodide (4.76 g, 25.05mmol) and ethynylmagnesium bromide (9.6 g, 75.15 mmol) at roomtemperature. The reaction mixture was further heated to reflux at 70° C.and stirred for another 12 h. The reaction mixture was filtered, dilutedwith water (50 mL) and concentrated in vacuo resulting in the crudecompound which was purified by column chromatography on silica geleluting with 0-20% ethyl acetate in n-hexane to afford 3.70 g, 60% yieldof the title compound as a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ=8.53(s, 4H), 3.59 (d, J=2.45 Hz, 4H), 3.13 (t, J=2.45 Hz, 2H), 2.37 (s, 4H),0.15 (s, 12H).

Example 51

N-(3-(1,1,3,3-tetramethyl-3-((pyrimidin-2-ylamino)methyl)disiloxanyl)propyl)isobutyramide[Example 51]

A solution of mixture ofN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene))bis(pyrimidin-2-amine)(500 mg, 1.436 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2-methylpropanamide)(567 mg, 1.436 mmol) in 4M HCl in dioxane (15 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 6 and 7. The mixture of 6 and 7 wasdissolved in acetonitrile (50 mL) and followed by addition of water(0.051 mL, 2.80 mmol), DIPEA (2.2 g, 17.05 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by chromatography onsilica with 0-30% ethyl acetate in n-hexane to afford 160 mg, 30% yield,of the title compound as colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.21(d, J=4.40 Hz, 2H), 7.62-7.69 (m, 1H), 6.82 (t, J=5.14 Hz, 1H), 6.48 (t,J=4.89 Hz, 1H), 2.97 (q, J=6.85 Hz, 2H), 2.75 (d, J=5.38 Hz, 2H), 2.31(quin, J=6.85 Hz, 1H), 1.32-1.42 (m, 2H), 0.97 (d, J=6.85 Hz, 6H),0.40-0.48 (m, 2H), 0.11 (s, 6H), 0.01 (s, 6H); MS (ES⁺): m/z=184.08[M/2+H]⁺; LCMS: t_(R)=1.42 min.

N,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(methylene))bis(pyrimidin-2-amine)(4)

A solution of (1,1,3,3-tetramethyldisiloxane-1,3-diyl)dimethanamine (3g, 15.35 mmol) in ethanol (10 mL) was charged with triethyl amine (12.8mL, 92.10 mmol) and 2-chloropyrimidine (3.5 g, 30.70 mmol) at roomtemperature. The reaction mixture was further heated to 60° C. for 2 h.The reaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by combiflash column chromatography elutingwith 0-10% methanol in DCM to afford 3.2 g, 60% yield of the titlecompound as colorless oil. MS (ES⁺): m/z=184.00 [M/2+18]⁺; LCMS:t_(R)=1.34 min.

(1,1,3,3-Tetramethyldisiloxane-1,3-diyl)dimethanamine (3)

A solution of 1,3-bis(azidomethyl)-1,1,3,3-tetramethyldisiloxane (4.5 g,18.41 mmol) in methanolic ammonia (150 mL) was charged with 10% Pd/C(450 mg, 10% by wt) under argon atmosphere. The reaction mixture wasstirred under hydrogen atmosphere in autoclave at room temperature for 2h. The reaction mixture was filtered through a pad of Celite and washedwith methanol. The filtrate was concentrated in vacuo to afford 2.86 g,90% yield, of the title compound as colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=2.48 (br. s, 4H), 2.01 (s, 2H), 0.06 (3, 12H).

1,3-Bis(azidomethyl)-1,1,3,3-tetramethyldisiloxane (2)

A solution of 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane (5 g,21.64 mmol) in DMF (50 mL) was charged with sodium azide (3 g, 47.61mmol) and sodium iodide (7 g, 47.61 mmol) at room temperature. Thereaction mixture was further heated to 90° C. for 12 h. The reactionmixture was concentrated in vacuo and the residue was stirred in ether(50 mL) and filtered. The filtrate was concentrated in vacuo to afford4.40 g, 85% yield, of the title compound as colorless oil. ¹H NMR (400MHz, DMSO-d₆) δ=2.76 (s, 4H), 0.09 (s, 12H).

Example 52 and Example 77

N-(3-(1,1,3,3-Tetramethyl-3-(2-(pyrimidin-2-yl)ethyl)disiloxanyl)propyl)isobutyramide[Example 52]

A solution of ((E)-N-(3-(1,1,3,3-tetramethyl-3-(2-(pyrimidin-2-yl)vinyl)disiloxanyl) propyl) isobutyramide (600 mg, 1.643 mmol) in THF (20 mL)was charged with Pd(OAc)₂ (73 mg, 0.328 mmol) and dimethyl ethoxy silane(512 mg, 4.931 mmol) and stirred at room temperature for 1 h. Thereaction mixture was concentrated in vacuo and the crude compound waspurified by Combi Flash chromatography on silica gel eluting with 0-10%methanol saturated with ammonia in DCM to afford 90 mg, 15% yield, ofthe title compound as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.72(d, J=4.89 Hz, 2H), 7.70 (br. s, 1H), 7.32 (t, J=4.89 Hz, 1H), 2.99 (q,J=6.52 Hz, 2H), 2.83-2.92 (m, 2H), 2.28-2.36 (m, 1H), 1.39 (td, J=7.83,15.65 Hz, 2H), 0.95-1.04 (m, 8H), 0.44-0.50 (m, 2H), 0.05 (s, 12H); MS(ES⁺): m/z=182.95 monomer [M+H]⁺; LCMS: t_(R)=1.89/2.12 min.

(E)-N-(3-(1,1,3,3-Tetramethyl-3-(2-(pyrimidin-2-yl)vinyl) disiloxanyl)propyl) isobutyramide [Example 77]

A solution of mixture of1,1,3,3-tetramethyl-1,3-bis((E)-2-(pyrimidin-2-yl)vinyl)disiloxane (1 g,2.923 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2-methylpropanamide)(1.13 g, 2.923 mmol) in 4M HCl in dioxane (20 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 5 and 6. The mixture of 5 and 6 wasdissolved in acetonitrile (50 mL) and followed by addition of water(0.105 mL, 5.846 mmol) and DIPEA (3 mL, 17.54 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by Combi Flashchromatography on silica gel eluting with 0-10% ethyl acetate inn-hexane to afford 1.02 g, 48% yield, of the title compound (mixture ofcis and trans) as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=(mixtureof cis and trans) 8.81 (d, J=4.89 Hz, 2H), 8.77 (t, J=5.38 Hz, 2H), 7.68(br. s, 2H), 7.39 (q, J=4.40 Hz, 4H), 7.27-7.36 (m, 1H), 6.96-7.06 (m,1H), 4.02-4.12 (m, 1H), 3.44 (dt, J=3.42, 15.16 Hz, 2H), 3.08-3.19 (m,2H), 3.00 (q, J=6.36 Hz, 4H), 2.32 (td, J=6.30, 13.33 Hz, 2H), 1.38-1.46(m, 4H), 0.98 (s, 6H), 0.97 (s, 6H), 0.20-0.32 (m, 12H), 0.07-0.12 (m,12H); MS (ES⁺): m/z=366.15 [M+H]⁺; LCMS: t_(R)=3.22/3.31 min.

1,1,3,3-Tetramethyl-1,3-bis((E)-2-(pyrimidin-2-yl)vinyl)disiloxane (3)

A solution of 2-chloropyrimidine (5 g, 43.85 mmol) in DMF (95 mL) wasadded 1,1,3,3-tetramethyl-1,3-divinyldisiloxane (4.07 g, 21.92 mmol),sodium acetate (10.8 g, 131.5 mmol), palladium acetate (982 mg, 4.385mmol) and tris-o-toluene phosphine (2.6 g, 8.771 mmol) at roomtemperature. The reaction mixture was further heated to reflux at 120°C. for 14 h and diluted with water and filtered through a pad of Celite.The separated organic layer was washed with water and separated. Theorganic layer was dried over Na₂SO₄, filtered and concentrated in vacuoresulting in the crude compound which was purified by combiflash columnchromatography on silica gel eluting with 0-20% ethyl acetate inn-hexane to afford 3.15 g, 21% yield, of the title compound as colorlessoil. MS (ES⁺): m/z=342.55 [M+H]⁺; LCMS: 181.08 (monomer); t_(R)=2.1 min.

Example 53

N-(3-(3-(3-azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide[Example 53]

A solution of mixture of1,3-bis(3-azidopropyl)-1,1,3,3-tetramethyldisiloxane (361 mg, 1.2 mmol)andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(400 mg, 1.2 mmol) were dissolved in 4M HCl in dioxane (10 mL) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude mixture of 4 and 5. Thecrude mixture was was charged with acetonitrile (10 mL) and water (43mg, 2.4 mmol) followed by DIPEA (931 mg, 7.2 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by chromatography onsilica gel chromatography eluting with 20-40% ethyl acetate in n-hexaneto afford 280 mg, 73% yield, of the title compound as colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=7.80 (br. s, 1H), 3.28 (t, J=6.85 Hz, 2H),2.93-3.01 (m, 2H), 1.76 (s, 3H), 1.49-1.58 (m, 2H), 1.32-1.41 (m, 2H),0.50-0.55 (m, 2H), 0.42-0.49 (m, 2H), 0.05 (s, 6H), 0.03 (s, 6H);(ESMS): m/z=339.00 [M+Na]⁺ and 360.85 [M+ACN]⁺

1,3-Bis(3-azidopropyl)-1,1,3,3-tetramethyldisiloxane (2)

A solution of 1,3-bis(3-chloropropyl)-1,1,3,3-tetramethyldisiloxane (3g, 10.4 mmol) in DMF (30 mL) was charged with sodium azide (1.49 g, 22.9mmol) and stirred at 90° C. for 12 h. The reaction mixture wasconcentrated in vacuo and reaction mixture was dissolved in diethylether. The preciptate was filtered of through a fritted funnel and thefiltrate was concentrated in vacuo to afford 2.80 g, 90% yield, of thetitle compound as colorless oil.

¹H NMR (400 MHz, DMSO-d₆) δ=3.28 (t, J=6.85 Hz, 4H), 1.49-1.59 (m, 4H),0.49-0.57 (m, 4H), 0.06 (s, 12H).

Example 54

N-(3-(3-(((5-(Azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)-2,2,2-trifluoroacetamide[Example 54]

A solution ofN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2,2,2-trifluoroacetamide)(447 mg, 0.9 mmol) and1,3-bis(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(400 mg, 0.9 mmol) was charged with 4M HCl in dioxane (10 mL) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude mixture of 4 and 5 whichwas charged with acetonitrile (10 mL) and water (32 mg, 1.8 mmol),followed by DIPEA (703 mg, 5.45 mmol) and stirred at room temperaturefor 1 h. The reaction mixture was concentrated in vacuo resulting in thecrude compound which was purified by chromatography on silica geleluting with 0-40% ethyl acetate in n-hexane to afford 249 mg, 59%yield, of the title compound as colorless oil. ¹H NMR (400 MHz, DMSO-d₆)δ=9.39 (br. s, 1H), 8.62-8.66 (m, 2H), 4.48 (s, 2H), 3.12 (q, J=6.85 Hz,2H), 2.38 (s, 2H), 1.41-1.52 (m, 2H), 0.43-0.51 (m, 2H), 0.15 (s, 6H),0.04 (s, 6H); MS (ES⁺): m/z=467.14 [M+H]⁺; LCMS: t_(R)=3.63 min.

N,N′-((1,1,3,3-Tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))bis(2,2,2-trifluoroacetamide)(2)

A solution of3,3′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propan-1-amine) (1 g,4.03 mmol) was charged with ethyl 2,2,2-trifluoroacetate (1.70 g, 12.09mmol) and stirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo until dryness to afford 1.76 g, 80% yield, of thetitle compound as colorless oil. The crude compound was used directlyfor next step without further purification. ¹H NMR (400 MHz, DMSO-d₆)δ=9.40 (br. s, 2H), 3.13 (q, J=6.85 Hz, 4H), 1.47 (td, J=7.83, 15.65 Hz,4H), 0.42-0.50 (m, 4H), 0.03 (s, 12H).

Example 55

2-(((3-(3-Azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)-5-(chloromethyl)pyrimidine[Example 55]

A solution of mixture1,3-bis(3-azidopropyl)-1,1,3,3-tetramethyldisiloxane (2.0 g, 6.66 mmol)and1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(3.19 g, 6.66 mmol) in 4M HCl in dioxane (50 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude mixture of 3 and 4 were charged with mixtureacetonitrile (20 mL) and water (239 mg, 13.32 mmol), and DIPEA (10.3 g,79.9 mmol) and stirred at room temperature for 1 h. The reaction mixturewas concentrated in vacuo resulting in the crude compound which waspurified by chromatography on silica gel eluting with 0-20% ethylacetate in n-hexane to afford 3.40 g, 85% yield, of the title compoundas a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.64 (s, 2H), 4.71 (s,2H), 3.20 (t, J=6.85 Hz, 2H), 2.34 (s, 2H), 1.42-1.52 (m, 2H), 0.44-0.50(m, 2H), 0.11 (s, 6H), 0.00 (s, 6H); MS (ES⁺): m/z=389.80 [M+H]⁺; LCMS:t_(R)=4.11 min.

Example 56

N-(3-(3-(((5-((2-Azidoethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide[Example 56]

A solution of mixture of1,3-bis(((5-((2-azidoethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(500 mg, 0.862 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(286 mg, 0.862 mmol) dissolved in 4M HCl in dioxane (20 mL) was stirredat room temperature for 1 h. The reaction mixture was concentrated invacuo resulting in the crude intermediate 7 and 8. The crude mixture of7 and 8 was charged with acetonitrile (60 mL) and water (0.031 mL, 17.24mmol) followed by DIPEA (0.89 mL, 51.72 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by chromatography onsilica gel eluting with 0-70% ethyl acetate in n-hexane to afford 595mg, 75% yield, of the title compound as a colorless oil. ¹H NMR (400MHz, DMSO-d₆) δ=8.58 (s, 2H), 7.77 (br. s, 1H), 4.51 (s, 2H), 3.64 (t,J=4.65 Hz, 2H), 3.42 (t, J=4.65 Hz, 2H), 2.95 (q, J=6.36 Hz, 2H),2.35-2.40 (m, 2H), 1.73-1.78 (m, 3H), 1.31-1.41 (m, 2H), 0.42-0.50 (m,2H), 0.15 (s, 6H), 0.04 (s, 6H); MS (ES⁺): m/z=457.29 [M+H]⁺; LCMS:t_(R)=3.25 min.

Example 57

N-(3-(3-(((5-((2-(2-Azidoethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide[Example 57]

A solution of mixture of1,3-bis(((5-((2-(2-azidoethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(500 mg, 0.748 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(248 mg, 0.748 mmol) in 4M HCl in dioxane (20 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 7 and 8. The mixture of intermediate7 and 8 was charged with acetonitrile (60 mL) and water (0.026 mL, 1.497mmol) followed by DIPEA (0.39 mL, 2.24 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 0-10% methanol in DCM toafford 530 mg, 71% yield, of the title compound as a colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=8.60 (s, 2H), 7.79 (br. s, 1H), 4.49 (s, 2H),3.62-3.57 (m, 6H), 3.37-3.42 (m, 2H), 2.93-3.02 (m, 2H), 2.40 (s, 2H),1.78 (s, 3H), 1.35-1.45 (m, 2H), 0.45-0.53 (m, 2H), 0.18 (s, 6H), 0.07(s, 6H); MS (ES⁺): m/z=501.37 [M+H]⁺; LCMS: t_(R)=3.21 min.

Example 58

N-(3-(3-((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide[Example 58]

A solution of mixture of1,3-bis(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(600 mg, 0.797 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(263 mg, 0.797 mmol) dissolved in 4M HCl in dioxane (20 mL) was stirredat room temperature for 1 h. The reaction mixture was concentrated invacuo resulting in the crude intermediate 7 and 8. The mixture ofintermediate 7 and 8 was charged with acetonitrile (60 mL) and water(0.014 mL, 0.797 mmol) followed by DIPEA (306 mg, 2.393 mmol) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 0-10% methanol inDCM to afford 430 mg, 50% yield, of the title compound as a colorlessoil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.60 (s, 2H), 7.79 (s, 1H), 4.49 (s,2H), 3.53-3.64 (m, 10H), 3.37-3.43 (m, 2H), 2.94-3.03 (m, 2H), 2.40 (s,2H), 1.78 (s, 3H), 1.35-1.45 (m, 2H), 0.45-0.53 (m, 2H), 0.18 (s, 6H),0.07 (s, 6H); MS (ES⁺): m/z=545.30 [M+H]⁺; LCMS: t_(R)=3.19 min.

Example 59

3-(3-(((5-((2-Azidoethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine[Example 59]

A solution of(9H-fluoren-9-yl)methyl(3-(3-(((5-((2-azidoethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate(4.4 g, 6.068 mmol) in saturated ethanolic ammonia (132 mL) was stirredat room temperature for 16 h. The reaction mixture was concentrated invacuo and the crude compound was purified by column chromatography onsilica gel eluting with 0-10% methanol saturated with ammonia in DCM toafford 1.1 g, 36% yield, of the title compound as a colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=8.62 (s, 2H), 4.54 (s, 2H), 3.64-3.69 (m, 2H),3.43-3.47 (m, 2H), 2.46-2.50 (m, 2H), 2.40 (s, 2H), 1.73-2.25 (m, 2H),1.30-1.41 (m, 2H), 0.46-0.54 (m, 2H), 0.18 (s, 6H), 0.07 (s, 6H); MS(ES⁺): m/z=415.15 [M+H]⁺; LCMS: t_(R)=2.31 min.

(9H-Fluoren-9-yl)methyl(3-(3-(((5-((2-azidoethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate(9)

A solution of mixture of1,3-bis(((5-((2-azidoethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(4.0 g, 6.896 mmol) and bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(4.7 g, 6.896 mmol) in 4M HCl in dioxane (100 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 7 and 8. The mixture of intermediate7 and 8 was dissolved in acetonitrile (300 mL) and followed by additionof water (0.25 mL, 13.79 mmol) and DIPEA (7.2 mL, 41.37 mmol) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 0-70% ethyl acetatein n-hexane to afford 4.40 g, 50.6% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.59 (s, 2H), 7.89 (d, J=7.34Hz, 2H), 7.69 (d, J=7.34 Hz, 2H), 7.37-7.45 (m, 2H), 7.27-7.35 (m, 3H),4.48-4.57 (m, 2H), 4.25-4.32 (m, 2H), 4.18-4.24 (m, 1H), 3.63-3.68 (m,2H), 3.41-3.46 (m, 2H), 2.95 (q, J=6.36 Hz, 2H), 2.36-2.42 (m, 2H), 1.42(td, J=7.46, 15.41 Hz, 2H), 0.44-0.52 (m, 2H), 0.17 (s, 6H), 0.06 (s,6H); MS (ES⁺): m/z=637.90 [M+H]⁺; LCMS: t_(R)=4.00 min.

1,3-Bis(((5-((2-azidoethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(5)

A solution of 2-azidoethan-1-ol (2.40 g, 28.70 mmol) in THF (300 mL) at0° C. was charged with sodium hydride (1.37 g, 34.44 mmol) and stirredat 0° C. for 30 min. The reaction mixture was then charged with1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(5.50 g, 11.48 mmol) and the resulting solution was stirred at 0° C. foranother 1 h. The reaction mixture was concentrated in vacuo resulting inthe crude compound which was purified by column chromatography on silicagel eluting with 0-100% ethyl acetate in n-hexane to afford 5.94 g, 60%yield, of the title compound as colorless oil.

¹H NMR (400 MHz, DMSO-d₆) δ=8.70 (s, 2H), 8.59 (s, 2H), 4.78 (s, 2H),4.52 (s, 2H), 3.64-3.67 (m, 2H), 3.58 (br. s, 2H), 3.41-3.46 (m, 2H),3.24-3.28 (m, 1H), 2.41 (d, J=2.93 Hz, 4H), 1.95-2.01 (m, 1H), 0.18 (s,12H).

Example 60

3-(3-(((5-((2-(2-Azidoethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine[Example 60]

A solution of(9H-fluoren-9-yl)methyl(3-(3-(((5-((2-(2-azidoethoxy)ethoxy)methyl)pyrimidin-2-yl) thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate (3.80 g, 5.24mmol) in saturated ethanolic ammonia (76 mL) was stirred at roomtemperature for 15 h. The reaction mixture was concentrated in vacuo andthe crude compound was purified by column chromatography on silica geleluting with 0-10% methanol saturated with ammonia in DCM to afford 950mg, 39% yield, of the title compound as colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=8.60 (s, 2H), 4.50 (s, 2H), 3.59-3.64 (m, 6H), 3.37-3.43 (m,2H), 2.46-2.50 (m, 2H), 2.40 (s, 2H), 1.76 (br. s, 2H), 1.32-1.41 (m,2H), 0.47-0.53 (m, 2H), 0.18 (s, 6H), 0.07 (s, 6H); MS (ES⁺): m/z=459.79[M+H]⁺; LCMS: t_(R)=2.23 min.

(9H-fluoren-9-yl)methyl(3-(3-(((5-((2-(2-azidoethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate(9)

A solution of mixture of1,3-bis(((5-((2-(2-azidoethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(3.70 g, 5.538 mmol) and bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(3.80 g, 5.538 mmol) in 4M HCl in dioxane (100 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 7 and 8. The mixture of intermediate7 and 8 was dissolved in acetonitrile (300 mL) and followed by additionof water (0.199 mL, 11.07 mmol) and DIPEA (5.76 mL, 33.23 mmol) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 0-10% methanol inDCM to afford 3.8 g, 50.6% yield, of the title compound as colorlessoil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.57 (s, 2H), 7.89 (d, J=7.34 Hz, 2H),7.69 (d, J=7.34 Hz, 2H), 7.39-7.45 (m, 2H), 7.25-7.35 (m, 3H), 4.48 (s,2H), 4.29 (d, J=6.85 Hz, 2H), 4.17-4.24 (m, 1H), 3.57-3.63 (m, 6H),3.35-3.41 (m, 2H), 2.95 (q, J=6.85 Hz, 2H), 2.39 (s, 2H), 1.42 (td,J=7.76, 15.28 Hz, 2H), 0.44-0.52 (m, 2H), 0.17 (s, 6H), 0.06 (s, 6H); MS(ES⁺): m/z=681.48 [M+H]⁺; LCMS: t_(R)=3.97 min.

1,3-Bis(((5-((2-(2-azidoethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(5)

A solution of 2-(2-azidoethoxy)ethan-1-ol (3.76 g, 28.70 mmol) in THF(300 mL) at 0° C. was charged with sodium hydride (1.37 g, 57.08 mmol)and stirred at 0° C. for 30 min. The cooled reaction mixture was thencharged with1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(5.5 g, 11.40 mmol) and stirred at 0° C. for an additional 1 h. Thereaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by column chromatography on silica geleluting with 0-5% methanol in DCM to afford 4.4 g, 58% yield, of thetitle compound as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.55-8.60(m, 4H), 4.60 (t, J=5.38 Hz, 4H), 4.48 (s, 4H), 3.44-3.53 (m, 12H), 2.40(s, 2H), 2.35 (s, 2H), 0.18 (s, 6H), 0.13 (s, 6H); MS (ES⁺): m/z=334.10[M/2+H]⁺; LCMS: t_(R)=2.65 min.

Example 61

3-(3-(((5-((2-(2-(2-Azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine[Example 61]

A solution of(9H-fluoren-9-yl)methyl(3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate(3.69 g, 5.089 mmol) in saturated ethanolic ammonia (73.8 mL) wasstirred at room temperature for 16 h. The reaction mixture wasconcentrated in vacuo and the crude compound was purified by columnchromatography on silica gel eluting with 0-10% methanol in DCM toafford 1.1 g, 44% yield, of the title compound as a colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=8.60 (s, 2H), 4.49 (s, 2H), 3.53-3.63 (m, 10H),3.36-3.42 (m, 2H), 2.47-2.50 (m, 2H), 2.40 (s, 2H), 1.77-1.93 (m, 2H),1.31-1.40 (m, 2H), 0.47-0.53 (m, 2H), 0.18 (s, 6H), 0.07 (s, 6H); MS(ES⁺): m/z=503.37 [M+H]⁺; LCMS: t_(R)=2.21 min.

(9H-fluoren-9-yl)methyl(3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy) ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate(9)

A solution of mixture of1,3-bis(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(4.89 g, 6.459 mmol) and bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(4.30 g, 6.459 mmol) in 4M HCl in dioxane (50 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 7 and 8. The mixture of intermediate7 and 8 was dissolved in acetonitrile (150 mL) and followed by additionof water (0.114 mL, 6.459 mmol) and DIPEA (3.3 mL, 19.37 mmol) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 70-100% ethylacetate in n-hexane to afford 3.69 g, 82% yield, of the title compoundas colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.56 (s, 2H), 7.88 (d,J=7.34 Hz, 2H), 7.67 (d, J=7.34 Hz, 2H), 7.36-7.43 (m, 2H), 7.31 (t,J=7.34 Hz, 2H), 7.27 (br. s, 1H), 4.45 (s, 2H), 4.27 (d, J=6.85 Hz, 2H),4.20 (d, J=6.36 Hz, 1H), 3.51-3.60 (m, 10H), 3.34-3.39 (m, 2H),2.90-2.98 (m, 2H), 2.38 (s, 2H), 1.34-1.45 (m, 2H), 0.43-0.50 (m, 2H),0.15 (s, 6H), 0.05 (s, 6H); MS (ES⁺): m/z=725.51 [M+H]⁺; LCMS:t_(R)=3.97 min.

1,3-Bis(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(5)

A solution of 2-(2-(2-azidoethoxy)ethoxy)ethan-1-ol (2.3 g, 13.14 mmol)in THF (500 mL) was cooled to 0° C. and charged with sodium hydride(1.62 g, 39.42 mmol) and stirred at 0° C. for 30 min. The reaction wascharged with1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(6.5 g, 13.14 mmol) and stirred at 0° C. for an additional 1 h. Thereaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by column chromatography on silica geleluting with 0-5% methanol in DCM to afford 5.94 g, 60% yield, of thetitle compound as a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.57 (s,4H), 4.57 (t, J=5.62 Hz, 2H), 4.47 (s, 4H), 3.46-3.63 (m, 22H), 2.41 (s,4H), 0.18 (s, 12H); MS (ES⁺): m/z=380.00 [M/2+H]⁺; LCMS: t_(R)=3.66 min.

Example 62

N-(3-(1,1,3,3-tetramethyl-3-(((5-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)pyrimidin-2-yl)thio)methyl)disiloxanyl)propyl)acetamide[Example 62]

A solution of ethynylbenzene (14.85 mg, 0.145 mmol) andN-(3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide(Example 43, 50 mg, 0.121 mmol) were dissolved in DMF (121 μl). Thereaction mixture was charged with sodium ascorbate (24.00 mg, 0.121mmol) in water (121 μl) followed by the addition of copper sulfatepentahydrate (28.5 mg, 0.091 mmol) in water (121 μl). After 5 min thereaction was complete and the reaction was worked up. The reactionmixture was partitioned between DCM and water and separated. The aqueouswas extracted with DCM (3×) and the combined DCM fractions were driedover Na₂SO₄, filtered and concentrated. The crude was purified by ISCOchromatography on silica gel [4 g cartridge, eluting with 0% of (10%NH₄OH in MeOH) in DCM to 8% of (10% NH₄OH in MeOH) in DCM] resulting in17.3 mg, 27.7% yield of the title compound as a clear colorless oil. ¹HNMR (CHLOROFORM-d, 400 MHz): δ (ppm) 8.55 (s, 2H), 7.79-7.83 (m, 2H),7.78 (s, 1H), 7.40-7.46 (m, 2H), 7.31-7.38 (m, 1H), 5.54 (s, 2H),3.16-3.23 (m, 2H), 2.96 (s, 1H), 2.89 (s, 1H), 2.41 (s, 2H), 1.97 (s,3H), 1.66 (s, 2H), 1.45-1.55 (m, 2H), 1.26 (s, 4H), 0.48-0.55 (m, 2H),0.21 (s, 6H), 0.08 (s, 6H), MS (ES+): m/z=515.34 [M+H]⁺; LCMS:t_(R)=2.20 min [polar_3 min_1500].

Example 63

Example 63

A solution ofN-(1,3-bis(prop-2-yn-1-yloxy)-2-((prop-2-yn-1-yloxy)methyl)propan-2-yl)acetamide(10.00 mg, 0.036 mmol) andN-(3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide [Example 58] (60.9 mg, 0.112 mmol) weredissolved in DMF (36.1 μl). The reaction mixture was charged with sodiumascorbate (7.14 mg, 0.036 mmol) in water (36.1 μl) followed by theaddition of copper sulfate pentahydrate (8.47 mg, 0.027 mmol) in water(36.1 μl). After 15 min the reaction mixture was checked by LCMS andfound to have a mass consistent with desired product. The reactionmixture was partitioned between DCM and water and separated. The aqueouswas extracted with DCM (3×) and the combined fractions were dried overNa₂SO₄, filtered and concentrated in vacuo resulting in a crude whichwas purified by ISCO chromatography on silica gel [4 g cartridge,eluting with 0% of (10% NH₄OH in MeOH) in DCM to 8% of (10% NH₄OH inMeOH) in DCM] resulting in 11.000 mg, 15.96% yield of the title compoundas a clear colorless oil.clear colorless oil. ¹H NMR (CHLOROFORM-d, 400MHz): δ (ppm) 8.50 (s, 6H), 7.71 (s, 3H), 6.28 (s, 1H), 5.73-5.86 (m,3H), 4.57 (s, 6H), 4.54 (t, J=5.2 Hz, 6H), 4.50 (s, 6H), 3.86-3.90 (m,6H), 3.81 (s, 6H), 3.63 (d, J=10.9 Hz, 23H), 3.18-3.25 (m, 6H), 2.41 (s,6H), 1.97 (s, 9H), 1.93 (s, 3H), 1.77 (s, 8H), 1.48-1.57 (m, 6H),0.50-0.57 (m, 6H), 0.21 (s, 18H), 0.09 (s, 18H), MS (ES+): m/z=1911.43,1912.44, 1913.23 [M+H]⁺; LCMS: t_(R)=2.31 min [polar_3 min_1500].

N-(1,3-bis(prop-2-yn-1-yloxy)-2-((prop-2-yn-1-yloxy)methyl)propan-2-yl)acetamide(3)

The title compound was prepared as described in the literature: J. Org.Chem., 2008, 73, 5602-56-5

Example 64 and Example 80

(S)-24-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-1-(1-((2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-((3S,5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)-1H-1,2,3-triazol-4-yl)-21-oxo-2,5,8,11,14,17-hexaoxa-20-azapentacosan-25-oicAcid [Example 80]

To an Eppendorf vial, DMF (219 μl) was added into a mixture of(S)-26-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oicacid (15.87 mg, 0.021 mmol) and (3R,5S,7R,9S)-methyl9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(18.2 mg, 0.016 mmol). More DMF (219 μL) was added to dissolve bothreactants. The vial was purged with nitrogen gas, capped, and sonicatedfor 5 mM. Then a freshly prepared solution of sodium ascorbate (100 mMin water, 32.9 μL, 3.29 μmol) in water (55 μL) was added, followed bythe addition of a freshly prepared solution of copper sulfatepentahydrate (100 mM in water, 32.9 μL, 3.29 μmol) in water (55 μL). Thevial was purged with nitrogen gas, capped, sonicated for 5 min, andagitated on a shaker at rt. A yellow suspension was formed. As thereaction proceeded, more solids went into the solution. After 2.5 h,LCMS showed mainly product. The reaction was stopped. The whole wasdissolved with 1.5 mL of DMSO, and passed through an ISCO solid loadingfilter plug with an aid of a vacuum. For the residue, dissolved with˜0.5 mL of DMSO and passed through the same filter plug. The combinedfiltrate (2 mL) was purified by a reversed phase preparative HPLC. Usingthe 10 mM ammonium bicarbonate in water and MeCN mobile phases withgradient 1 for reverse phase preparative HPLC to obtain 6.15 mg, 20.2%yield of the title compound as a light yellow solid after lyophilizing1.51 min LCMS using acidic mobile phase and method [polar_3 min_0_1500](M+2)=1851.2, (M+2)/2=926.0, (M+3)/3=617.7, (M+4)/4=463.6. ¹H NMR (400MHz, DMSO-d₆) δ ppm 0.01-0.09 (m, 7H) 0.16 (s, 7H) 0.43-0.55 (m, 2H)0.63 (br s, 1H) 0.70-0.88 (m, 7H) 1.09-1.37 (m, 7H) 1.38-1.66 (m, 5H)1.81-2.09 (m, 6H) 2.16 (brd, J=7.07 Hz, 2H) 2.27-2.43 (m, 6H) 2.60-2.77(m, 8H) 2.89 (brd, J=9.85 Hz, 2H) 3.01-3.22 (m, 15H) 3.43-3.57 (m, 18H)3.71 (s, 5H) 3.83 (br d, J=5.81 Hz, 1H) 3.91-4.11 (m, 3H) 4.23 (br s,1H) 4.43-4.55 (m, 4H) 5.52-5.73 (m, 5H) 6.19 (s, 1H) 6.44 (s, 1H)6.54-6.70 (m, 3H) 6.86-7.05 (m, 5H) 7.26 (d, J=8.08 Hz, 1H) 7.37 (d,J=7.83 Hz, 1H) 7.63 (br d, J=8.34 Hz, 2H) 7.77 (br t, J=5.68 Hz, 1H)7.89 (br s, 1H) 8.09 (br s, 1H) 8.20 (s, 1H) 8.48-8.73 (m, 4H) 9.33 (s,1H). MS (ES+): m/z=(M+2)=1851.2, (M+2)/2=926.0, (M+3)/3=617.7,(M+4)/4=463.6. [M+H]⁺; LCMS: t_(R)=1.51 min [polar_3 min_1500].

Methyl(3R,5S,7R,9S)-9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate[Example 64]

A solution of (3R,5S,7R,9S)-methyl5-ethyl-9-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-5-(hydrazinecarbonyl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(200 mg, 0.260 mmol) in acetonitrile (3.34 ml) was cooled to −10° C. andcharged with 1 M HCl in water (12.33 ml, 12.33 mmol) and maintained at−10° C. then charged with solid sodium nitrite (41.3 mg, 0.598 mmol)(Note: upon addition of NaNO₂ the color changed from paleyellow/colorless to a yellowish brown color) After 10 min the yellowishbrown solution was adjusted to pH ˜8.00 with dropwise addition of coldsat NaHCO₃ solution (˜13.2 mL of NaHCO₃ added). The solution wasextracted rapidly with DCM (5×10 mL) and the combined organic layerswere washed with brine (1×20 mL) and dried over Na₂SO₄, filtered, andconcentrated to ˜8.00 mL-10 mL cooled to 0° C. and charged with asolution of3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine[Example 44] (96 mg, 0.260 mmol) in DCM (8.0 mL) and allowed to stir at0° C. for 2 hr. The reaction mixture was concentrated in vacuo resultingin a light tan solid. The crude was further purified by chromatographyon silica gel [ISCO CombiFlash, 12 g Gold cartridge, eluting with 0% of(10% 7N NH3 in MeOH) to 8% (10% 7N NH3 in MeOH) in DCM resulting in 127mg, 44% yield of the title compound as a pale yellow foam solid. ¹H NMR(CHLOROFORM-d, 400 MHz): δ (ppm) 9.47-9.59 (m, 1H), 8.49 (s, 2H), 8.04(s, 1H), 7.54 (d, J=8.1 Hz, 1H), 7.15-7.21 (m, 3H), 7.08-7.14 (m, 1H),6.61 (s, 1H), 6.08 (s, 1H), 5.84 (s, 2H), 4.34 (s, 2H), 4.19 (d, J=4.8Hz, 1H), 3.92-4.03 (m, 1H), 3.78 (s, 3H), 3.63-3.74 (m, 1H), 3.61 (s,3H), 3.38-3.45 (m, 2H), 3.07-3.37 (m, 8H), 2.83-2.89 (m, 1H), 2.79-2.83(m, 5H), 2.62 (s, 1H), 2.60 (d, J=4.8 Hz, 1H), 2.37-2.50 (m, 4H),2.24-2.33 (m, 1H), 1.98-2.10 (m, 1H), 1.68-1.83 (m, 2H), 1.52-1.60 (m,4H), 1.45-1.51 (m, 1H), 1.37-1.45 (m, 1H), 1.21-1.36 (m, 4H), 0.87-1.00(m, 7H), 0.85 (br d, J=6.1 Hz, 1H), 0.54-0.62 (m, 2H), 0.19-0.25 (m,6H), 0.10 (s, 6H), MS (ES+): m/z=1107.61, 1108.56 [M+H]⁺; LCMS:t_(R)=1.62 min [polar_3 min_1500].

Methyl(3R,5S,7R,9S)-9-03aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(3)

A solution of hydrazine (12.77 ml, 407 mmol) in Ethanol (15.03 ml) wascharged with (3aR,3a1R,4R,5S,5aR,10bR)-methyl4-acetoxy-3a-ethyl-9-((3R,5S,7R,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-5-hydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxylate,sulfuric acid salt (2.5 g, 2.75 mmol) and heated to 60° C. under a N₂atmosphere. The reaction mixture was heated to 60° C. for 16 h thenstirred at rt for an additional 6 hrs. The reaction mixture was pouredinto 90 mL of HPLC grade water and the aqueous was extracted with 5×90mL of DCM and the combined organic fractions were washed with water 1×90mL and brine 1×120 mL and dried over anhydrous Na₂SO₄, filtered andconcentrated in vacuo resulting in crude product that was furtherpurified by column chromatography on silica gel [ISCO Combiflash, 12 ggold catridge] eluting with a gradient of 100% DCM to 8% 7N NH3 in MeOHin DCM] resulting in 1.42 g, 67.1% yield of the title compound as anoff-white solid. ¹H NMR (DMSO-d₆, 400 MHz): δ (ppm) 9.31 (s, 1H),8.87-9.03 (m, 1H), 8.81 (br s, 1H), 8.33 (s, 1H), 7.37 (d, J=7.8 Hz,1H), 7.26 (d, J=8.1 Hz, 1H), 6.96-7.04 (m, 1H), 6.88-6.95 (m, 1H), 6.45(s, 1H), 6.20 (s, 1H), 5.76 (s, 2H), 5.66-5.72 (m, 1H), 5.54-5.62 (m,1H), 4.23 (br d, J=3.8 Hz, 2H), 4.12 (br d, J=3.5 Hz, 1H), 4.05 (br dd,J=15.2, 13.6 Hz, 1H), 3.90-3.97 (m, 2H), 3.82 (d, J=6.1 Hz, 1H),3.65-3.78 (m, 4H), 3.54 (s, 3H), 3.36 (s, 1H), 3.26 (br d, J=14.1 Hz,1H), 3.03-3.22 (m, 4H), 2.89 (br dd, J=14.4, 4.5 Hz, 1H), 2.61-2.77 (m,6H), 2.28-2.42 (m, 2H), 1.97-2.05 (m, 1H), 1.88-1.97 (m, 1H), 1.74 (s,2H), 1.51-1.66 (m, 2H), 1.25-1.38 (m, 2H), 1.12-1.21 (m, 3H), 0.71-0.85(m, 6H), 0.56-0.67 (m, 1H), MS (ES+): m/z=769.40, 770.41 [M+H]⁺; LCMS:t_(R)=132 min [polar_3 min_1500].

Compound 6

(R)-26-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oicAcid (6)

A solution oftert-butyl(R)-26-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate5 (1.66 g, 2.080 mmol) in DCM (50 mL) was charged with trifluoroaceticacid (50 mL) and stirred at room temperature for 12 h. The reactionmixture was concentrated in vacuo resulting in the crude compound whichwas purified by reverse phase combiflash column chromatography(acetonitrile:water: 0.1% TFA) to afford 650 mg, 42% yield of the titlecompound as a yellow solid. ¹H NMR (400 MHz, DMSO-d₆) δ=12.49 (s, 1H),8.66 (s, 1H), 8.20 (d, J=7.34 Hz, 1H), 7.87-7.94 (m, 1H), 7.65 (d,J=8.31 Hz, 2H), 7.12 (br. s, 2H), 6.63 (d, J=8.31 Hz, 2H), 4.49 (s, 2H),4.22-4.32 (m, 1H), 4.13 (d, J=2.45 Hz, 2H), 3.45-3.56 (m, 20H), 3.43 (t,J=2.20 Hz, 1H), 3.36 (t, J=5.87 Hz, 2H), 3.17 (q, J=5.87 Hz, 2H),2.14-2.24 (m, 2H), 1.99-2.08 (m, 1H), 1.84-1.96 (m, 1H); MS (ES⁺):m/z=743.41 [M+H]⁺; LCMS: t_(R)=1.83 min.

tert-Butyl(R)-26-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate(5)

A solution oftert-butyl(R)-26-(4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate(2.0 g, 2.237 mmol) in DMF (40 mL) was charged with 0.1M solution ofpiperdine (40 mL) and stirred at room temperature for 3 h. The reactionmixture was concentrated in vacuo resulting in the crude compound. Thecrude compound was stirred in diethyl ether (40 mL) for 10 min and thesolid was filtered and washed with diethyl ether (20 mL) and dried toafford 1.60 g (90% yield) of the title compound as yellow solid. ¹H NMR(400 MHz, DMSO-d₆) δ=8.64 (s, 1H), 8.16-8.21 (m, 1H), 7.91 (t, J=5.62Hz, 1H), 7.64 (d, J=8.31 Hz, 2H), 6.95 (t, J=5.87 Hz, 1H), 6.63 (d,J=8.80 Hz, 2H), 4.48 (d, J=5.38 Hz, 2H), 4.16-4.23 (m, 1H), 4.13 (d,J=1.96 Hz, 2H), 3.45-3.57 (m, 20H), 3.13-3.20 (m, 2H), 2.93-2.98 (m,2H), 2.14-2.23 (m, 2H), 1.85-2.03 (m, 2 H), 1.52-1.64 (m, 4H), 1.39 (s,9H); MS (ES⁺): m/z=799.40 [M+H]⁺; LCMS: t_(R)=2.20 min.

tert-Butyl(R)-26-(4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate(4)

A solution of 2,5-dioxopyrrolidin-1-yl4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzoate(2.10 g, 4.158 mmol) andtert-butyl(R)-26-amino-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate(2.09 g, 4.158 mmol) in DMF (40 mL) was added DIPEA (1.44 mL, 8.316mmol) under nitrogen atmosphere for 4 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound. The crudecompound was stirred in diethyl ether (250 mL) for 15 min and the solidprecipitated was filtered and washed with diethyl ether (100 mL) anddried to afford 3.25 g, 87% yield of the title compound as off whitesolid. ¹H NMR (400 MHz, DMSO-d₆) δ=8.73-8.78 (m, 1H), 8.62 (s, 1H), 7.89(d, J=7.34 Hz, 3H), 7.63 (d, J=7.83 Hz, 2H), 6.88 (s, 3H), 5.11 (br. s,2H), 4.20-4.28 (m, 1H), 4.13 (s, 2H), 3.45-3.58 (m, 17H), 3.38 (dd,J=5.87, 12.23 Hz, 4H), 3.13-3.22 (m, 2H), 2.17-2.28 (m, 2H), 1.84-2.09(m, 4H), 1.40 (s, 9H); MS (ES⁺): m/z=895.30 [M+H]⁺; LCMS: t_(R)=2.48min.

tert-Butyl(R)-26-amino-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate(3)

A solution oftert-butyl(R)-26-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate(9 g, 12.39 mmol) in saturated ethanolic ammonia (50 mL) in a seal tubewas stirred at room temperature for 16 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby flash column chromatography eluting with 0-10% methanol in DCM toafford 4.68 g (75% yield) of the title compound as a colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=6.65 (s, 1H), 6.08 (s, 2H), 4.21 (d, J=2.45 Hz,2H), 3.59-3.72 (m, 19H), 3.54-3.57 (m, 2H), 3.42-3.48 (m, 2H), 3.34 (dd,J=4.65, 9.05 Hz, 1H), 2.42-2.46 (m, 1H), 2.31-2.37 (m, 2H), 2.05-2.15(m, 1H), 1.73-1.83 (m, 2H), 1.46 (s, 9H); MS (ES⁺): m/z=505.00 [M+H]⁺;LCMS: t_(R)=2.46 min.

tert-Butyl(R)-26-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oate(2)

A solution of 3,6,9,12,15,18-hexaoxahenicos-20-yn-1-amine (7 g, 21.94mmol) in DMF (25 mL) was charged with Fmoc-Glu-Ot-Bu (mg, 21.94 mmol),HATU (12.5 g, 32.91 mmol) and DIPEA (4.2 mL, 32.91 mmol) and was stirredat room temperature for 16 h. The reaction mixture was diluted withwater and extracted with ethyl acetate. The combined organic layers weredried over anhydrous Na₂SO₄, filtered and concentrated in vacuoresulting in a crude compound which was purified by columnchromatography on combiflash eluting with 0-5% methanol in DCM to afford9.2 g, 58% yield, of the title compound as an off white semisolid.

¹H NMR (400 MHz, CDCl₃) δ=7.77 (d, J=7.34 Hz, 2H), 7.59-7.64 (m, 2H),7.38-7.43 (m, 2H), 7.29-7.35 (m, 2H), 6.57 (br. s, 1H), 5.78 (d, J=7.83Hz, 1H), 4.39 (dq, J=7.34, 10.76 Hz, 2H), 4.22 (t, J=7.09 Hz, 2H), 4.19(d, J=2.45 Hz, 2H), 3.59-3.70 (m, 20H), 3.53-3.57 (m, 2H), 3.41-3.47 (m,2H), 2.43 (t, J=2.45 Hz, 1H), 2.22-2.32 (m, 2H), 1.47 (s, 9H), 1.23-1.27(m, 2H); MS (ES⁺): m/z=727.51 [M+H]⁺; LCMS: t_(R)=3.18 min.

2,5-Dioxopyrrolidin-1-yl4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzoate(1a)

A solution of4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzoicacid (550 mg, 1.348 mmol) in DMF (20 mL) was charged with NHS (186 mg,1.617 mmol), DCC (333 mg, 1.617 mmol) and was stirred at roomtemperature for 14 h. The reaction mixture was quenched with water (25mL), filtered and washed with water (20 mL) and dried resulting in thecrude compound (580 mg). The crude compound was stirred in methanol (25mL) for 1 h at room temperature. The solid was filtered and washed withmethanol (5 mL) and dried to afford 350 mg, 51% yield, of the titlecompound as an off white solid. ¹H NMR (400 MHz, DMSO-d₆) δ=11.47 (br.s, 1H), 8.65 (s, 1H), 8.16 (d, J=8.31 Hz, 2H), 7.80 (d, J=8.31 Hz, 2H),5.57 (d, J=7.82 Hz, 2H), 2.89 (br. s, 2H), 1.68-1.76 (m, 2H), 1.57-1.66(m, 2H); MS (ES⁺): m/z=506.30 [M+H]⁺; LCMS: t_(R)=2.22 min.

Example 65

N-(3-(3-(((5-((2-(2-(2-(4-benzyl-1H-1,2,3-triazol-1-yl)ethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide[Example 65]

A solution ofN-(3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide[Example 58] (30 mg, 0.055 mmol) and prop-2-yn-1-ylbenzene (6.72 mg,0.058 mmol) were dissolved in DMF (55.1 μl) and charged with sodiumascorbate (10.91 mg, 0.055 mmol) in water (55.1 μl) followed by theaddition of copper sulfate pentahydrate (12.94 mg, 0.041 mmol) in water(55.1 μl) and allowed to stir for 30 min. The reaction mixture waspartitioned between DCM and water and separated. The aqueous wasextracted with DCM (3×) and the combined organic fractions were washedwith brine (1×), dried over Na₂SO₄, filtered, and concentrated in vacuoresulting in 24 mg, 66% yield of the title compound as a pale yellowoil. 1HNMR (CHLOROFORM-d, 400 MHz): δ (ppm) 8.38 (s, 2H), 7.06-7.23 (m,5H), 5.57 (br s, 1H), 4.32-4.44 (m, 4H), 3.98 (s, 2H), 3.74 (t, J=5.2Hz, 2H), 3.42-3.53 (m, 8H), 3.07-3.18 (m, 2H), 2.31 (s, 2H), 1.84-1.93(m, 3H), 1.36-1.47 (m, 2H), 0.38-0.50 (m, 2H), 0.09-0.14 (m, 6H),−0.06-0.02 (m, 6H), MS (ES+): m/z=661.41[M+H]⁺; LCMS: t_(R)=2.17 min[polar_3 min_1500].

Example 66

N-(3-(3-(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide[Example 66]

A solution of1,3-bis(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(4.90 g, 4.799 mmol) andN,N-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(3.30 g, 4.799 mmol) in 4M HCl in dioxane (100 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 5 and 6. The intermediate 5 and 6was dissolved in acetonitrile (250 mL) and followed by addition of water(250 mL) and DIPEA (4.90 mL, 28.79 mmol) and stirred at room temperaturefor another 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by combiflashchromatography on silica gel eluting with 50-80% ethyl acetate inn-hexane to afford 3.56 g, 55% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.60 (s, 2H), 7.76-7.82 (m,1H), 4.47-4.51 (m, 2H), 3.49-3.64 (m, 22H), 3.37-3.42 (m, 2H), 2.94-3.02(m, 2H), 2.36-2.42 (m, 2H), 1.78 (s, 3H), 1.34-1.45 (m, 2H), 0.44-0.53(m, 2H), 0.18 (s, 6H), 0.07 (s, 6H); MS (ES⁺): m/z=676.70 [M+H]⁺; LCMS:t_(R)=3.27 min.

1,3-Bis(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(3)

A solution of 17-azido-3,6,9,12,15-pentaoxaheptadecan-1-ol (3 g, 9.771mmol) in THF (250 mL) at 0° C. was charged with sodium hydride (502 mg,14.65 mmol) and stirred at same temperature for 30 min. Followed byaddition of1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(7 g, 14.65 mmol) to the resulting solution and was stirred at the sametemperature for another 1 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by combiflashcolumn chromatography eluting with 0-5% methanol in DCM to afford 5.90g, 60% yield, of the title compound as colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=8.60 (s, 1H), 8.57 (s, 3H), 4.46-4.49 (m, 4H), 3.49-3.63 (m,45H), 3.36-3.43 (m, 6H), 2.39-2.42 (m, 4H), 0.18 (s, 9H); MS (ES⁺):m/z=511.40 [M/2+H]⁺; LCMS: t_(R)=3.53 min.

Example 67

(9H-fluoren-9-yl)methyl(3-(3-(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate[Example 67]

A solution of1,3-bis(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(1 g, 0.979 mmol) and bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(325 mg, 0.979 mmol) in 4M HCl in dioxane (30 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 5 and 6. The mixture of intermediate5 and 6 was dissolved in acetonitrile (50 mL) and followed by additionof water (0.07 mL, 3.917 mmol), DIPEA (1.01 mL, 5.876 mmol) and stirredat room temperature for 1 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by combiflashcolumn chromatography eluting with 50-80% ethyl acetate in n-hexane toafford 584 mg, 35% yield, of the title compound as a colorless oil. ¹HNMR (400 MHz, DMSO-d₆) δ=8.54 (s, 2H), 7.85 (d, J=7.34 Hz, 2H), 7.64 (d,J=7.34 Hz, 2H), 7.34-7.40 (m, 2H), 7.25-7.31 (m, 3H), 4.43 (s, 2H), 4.25(d, J=6.85 Hz, 2H), 4.13-4.19 (m, 1H), 3.45-3.57 (m, 20H), 3.34 (t,J=5.14 Hz, 2H), 3.28 (s, 2H), 2.91 (q, J=6.68 Hz, 2H), 2.35 (s, 2H),1.33-1.44 (m, 2H), 0.41-0.47 (m, 2H), 0.13 (s, 6H), 0.02 (s, 6H); MS(ES⁺): m/z=856.65 [M+H]⁺; LCMS: t_(R)=4.07 min.

Example 68

A solution oftert-butyl(1,3-bis((4-ethynylbenzyl)oxy)-2-(((4-ethynylbenzyl)oxy)methyl) propan-2-yl)carbamate (10.00 mg, 0.018 mmol) andN-(3-(3-(((4-(azidomethyl) phenyl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide (22.59 mg, 0.055mmol) were dissolved in DMF (40.0 μl). The reaction mixture was chargedwith a solution of sodium ascorbate (1.757 mg, 8.87 μmol) in water (80μl) followed by the addition of a solution of copper sulfatepentahydrate (2.78 mg, 8.87 μmol) in water (80 μl). After 5 min thereaction mixture was partitioned between DCM and water and separated.The aqueous was extracted with DCM (3×) and the combined organicfractions dried over Na₂SO₄, filtered and concentrated in vacuo. Theresulting in crude e material was purified by ISCO chromatography onsilica gel [4 g cartridge, eluting with 0% of (10% NH₄OH in MeOH) in DCMto 8% of (10% NH₄OH in MeOH) in DCM] resulting in 11 mg, 20.13% yield ofthe title compound as a clear colorless oil. ¹H NMR (CHLOROFORM-d, 400MHz): δ (ppm) 8.55 (s, 6H), 7.69 (s, 3H), 5.96 (s, 1H), 5.65-5.82 (m,3H), 5.52 (s, 6H), 4.58 (s, 6H), 3.76 (s, 6H), 3.14-3.25 (m, 7H), 2.40(s, 6H), 1.96 (s, 9H), 1.91 (s, 3H), 1.71 (s, 7H), 1.46-1.56 (m, 7H),0.49-0.55 (m, 6H), 0.20 (s, 18H), 0.08 (s, 18H), MS (ES⁺): m/z=1514.96,1516.02 [M+H]⁺; LCMS: t_(R)=2.27 min [nonpolar_3 min].

Example 69

N-(3-(1,1,3,3-tetramethyl-3-(3-(4-phenyl-1H-1,2,3-triazol-1-yl)propyl)disiloxanyl)propyl)acetamide [Example 69]

Phenyl acetylene (5 μL, 0.046 mmol) andN-(3-(3-(3-azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide(21.6 mg, 0.068 mmol) were dissolved with DMF (114 μL). Sodium ascorbate(2.71 mg, 0.014 mmol) in water (114 μL) was added, followed by coppersulfate pentahydrate (1.43 mg, 4.55 μmol) in water (114 μL). The vialwas purged with nitrogen gas, capped, sonicated for 5 min, and agitatedon a shaker at rt. The blue solution became a yellow solid in a minute.After 10 min, the reaction was quenched with water. The product wasextracted with EtOAc. The organic layer was washed with brine, driedover Na₂SO₄, filtered, and concentrated in vacuo. The crude was purifiedby column chromatography (solid loading) on silica gel eluting with50:50 to 30:70 Hex:EtOAc to afford 14 mg, 73.4% yield of the titlecompound as a clear film. ¹H NMR (400 MHz, CHLOROFORM-d) δ ppm 0.04-0.06(m, 6H) 0.07-0.09 (m, 6H) 0.43-0.62 (m, 4H) 1.40-1.57 (m, 2H) 1.92-2.08(m, 5H) 3.14-3.31 (m, 2H) 4.39 (t, J=7.07 Hz, 2H) 7.31-7.38 (m, 1H)7.41-7.48 (m, 2H) 7.79 (s, 1H) 7.82-7.88 (m, 2H), MS (ES⁺): m/z=419.36[M+H]⁺; LCMS: t_(R)=2.22 min [polar_3 min_0_1500].

Example 70

(9H-fluoren-9-yl)methyl(3-(3-(3-azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate [Example 70]

A solution of 1,3-bis(3-azidopropyl)-1,1,3,3-tetramethyldisiloxane (400mg, 1.333 mmol) andbis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(923 mg, 1.333 mmol) in 4M HCl in dioxane (30 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 4 and 5. The intermediate 4 and 5was dissolved in acetonitrile (50 mL) and followed by addition of water(0.95 mL) and DIPEA (1.34 mL, 7.999 mmol) and stirred at roomtemperature for another 1 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by combiflashcolumn chromatography on silica gel eluting with 10-30% ethyl acetate inn-hexane to afford 541 mg, 41% yield, of the title compound as a whitesolid. ¹H NMR (400 MHz, DMSO-d₆) δ=7.84-7.90 (m, 2H), 7.67 (d, J=7.34Hz, 2H), 7.37-7.42 (m, 2H), 7.30 (t, J=7.58 Hz, 2H), 7.23-7.27 (m, 1H),4.27 (d, J=6.85 Hz, 2H), 4.20 (d, J=6.36 Hz, 1H), 3.26 (t, J=6.85 Hz,2H), 2.93 (q, J=6.52 Hz, 2H), 1.48-1.57 (m, 2H), 1.39 (td, J=7.64, 15.53Hz, 2H), 0.49-0.55 (m, 2H), 0.41-0.48 (m, 2H), 0.04 (s, 6H), 0.03 (s,6H); MS (ES⁺): m/z=338 [M+H]⁺ monomer; LCMS: t_(R)=4.39 min.

1,3-Bis(3-azidopropyl)-1,1,3,3-tetramethyldisiloxane (2)

A solution of 1,3-bis(3-chloropropyl)-1,1,3,3-tetramethyldisiloxane (1g, 3.484 mmol) in DMF (20 mL) was charged with sodium iodide (1.03 g,6.912 mmol) and sodium azide (566 mg, 8.707 mmol) at room temperature.The reaction mixture was heated to 90° C. for 14 h. The reaction mixturewas concentrated in vacuo, the residue was diluted with water andextracted with DCM (3×). The combined organic layers were dried overanhydrous Na₂SO₄, filtered and concentrated in vacuo to afford 810 mg,78% yield, of the title compound as a colorless oil. ¹H NMR (400 MHz,DMSO-d₆) δ=3.26-3.31 (m, 4H), 1.49-1.59 (m, 4H), 0.50-0.56 (m, 4H), 0.06(s, 12H).

Example 71

2,5-Dioxopyrrolidin-1-yl4-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanoate[Example 71]

A solution of4-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanoicacid (1 g, 3.007 mmol) in DCM (20 mL) was charged with DCC (619 mg,3.007 mmol) and N-hydroxysuccinimide (345 mg, 3.007 mmol) and stirred atroom temperature for another 2 h. The reaction mixture was concentratedin vacuo, diluted with acetonitrile and re-concentrated. The slurry wascooled and the solid was filtered and washed. The filtrate wasconcentrated in vacuo, resulting in the crude compound which waspurified by combiflash column chromatography eluting with 10-30% ethylacetate in n-hexane to afford 1.2 g (81% yield) of the title compound asa colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.64 (s, 2H), 4.47 (s, 2H),2.78 (s, 4H), 2.64 (t, J=6.85 Hz, 2H), 2.38 (s, 2H), 1.58-1.69 (m, 2H),0.56-0.63 (m, 2H), 0.12-0.17 (m, 6H), 0.02-0.06 (m, 6H); MS (ES+):m/z=497.29; LCMS: t_(R)=3.58 min.

4-(3-(((5-(Azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)butanoic Acid (5)

A solution of1,3-bis(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(1.5 g, 3.048 mmol) and4,4′-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)dibutyric acid (932 mg,3.048 mmol) in 4M HCl in dioxane (30 mL) was stirred at room temperaturefor 1 h. The reaction mixture was concentrated in vacuo resulting in thecrude intermediate 3 and 4. The intermediate 3 and 4 was dissolved inacetonitrile (200 mL) and followed by addition of water (0.11 mL, 6.097mmol) and DIPEA (3.09 mL, 18.29 mmol) and stirred at room temperaturefor another 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by combiflash columnchromatography on silica gel eluting with 10-30% ethyl acetate inn-hexane to afford 1.2 g, 50% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=11.95 (s, 1H), 8.67 (s, 2H),4.50 (s, 2H), 2.39-2.44 (m, 2H), 2.22 (dt, J=3.67, 7.21 Hz, 2H),1.48-1.60 (m, 2H), 0.52 (td, J=4.59, 12.35 Hz, 2H), 0.18 (s, 6H), 0.06(s, 6H).

Example 72 and Example 82

Methyl(3R,5S,7R,9S)-9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate[Example 72]

A solution of (3R,5S,7R,9S)-methyl5-ethyl-9-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-5-(hydrazinecarbonyl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(100 mg, 0.130 mmol) in acetonitrile (1.67 ml) and 1 M HCl in water(6.16 ml, 6.16 mmol) cooled to −10° C. then charged with sodium nitrite(20.64 mg, 0.299 mmol). After 10 min the yellowish brown solution wasadjusted to pH ˜8.00 dropwise adding cold sat NaHCO₃ solution (˜6.6 mLof NaHCO₃ added). The solution was extracted rapidly with DCM (5×5.0 mL)and the combined organic layers were washed with brine (1×10 mL) anddried over Na₂SO₄, filtered and concentrated to ˜4.00 mL cooled to 0° C.in and charged with a solution of3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine(65.4 mg, 0.130 mmol) in 4.0 mL of DCM and allowed to stir at 0° C. for2 hr. The reaction mixture was concentrated in vacuo resulting in alight tan solid which was purified by chromatography on silica gel [ISCOCombiFlash, 12 g Gold cartridge, eluting with 0% of (10% 7N NH3 in MeOH)to 8% (10% 7N NH3 in MeOH) in DCM resulting in 65.5 mg, 41% yield of thetitle compound as a light yellow solid. ¹H NMR (DMSO-d₆, 400 MHz): δ(ppm) 9.33 (s, 1H), 8.58 (s, 2H), 8.51 (s, 1H), 7.77 (br t, J=5.8 Hz,1H), 7.37 (d, J=8.1 Hz, 1H), 7.26 (d, J=8.1 Hz, 1H), 7.00 (t, J=7.6 Hz,1H), 6.88-6.95 (m, 1H), 6.44 (s, 1H), 6.19 (s, 1H), 5.69 (br dd, J=10.7,5.4 Hz, 1H), 5.54-5.61 (m, 1H), 4.47 (s, 2H), 4.00-4.10 (m, 1H), 3.96(s, 1H), 3.92 (s, 1H), 3.83 (d, J=5.8 Hz, 1H), 3.68-3.76 (m, 4H),3.49-3.62 (m, 13H), 3.36-3.40 (m, 2H), 3.30-3.34 (m, 6H), 2.98-3.28 (m,7H), 2.84-2.93 (m, 1H), 2.59-2.77 (m, 6H), 2.52-2.55 (m, 1H), 2.48-2.52(m, 7H), 2.30-2.42 (m, 4H), 1.89-2.05 (m, 2H), 1.42-1.65 (m, 4H),1.12-1.36 (m, 5H), 0.69-0.85 (m, 6H), 0.57-0.68 (m, 1H), 0.46-0.55 (m,2H), 0.17 (s, 6H), 0.07 (s, 6H), MS (ES+): m/z=1240.00, 1240.90 [M+H]⁺;LCMS: t_(R)=1.65 min [polar_3 min_1500].

(31S)-31-(4-(((2-Amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-1-(1-(2-(2-(2-((2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-((5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl) thio)pyrimidin-5-yl)methoxy) ethoxy) ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)-4,4-bis(((1-(2-(2-(2-(2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-((5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methoxy)ethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)methoxy)methyl)-6,28-dioxo-2,9,12,15,18,21,24-heptaoxa-5,27-diazadotriacontan-32-oicAcid [Example 82]

To an Eppendorf vial, DMF (134 μL) was added to a mixture of(S)-33-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oicacid (10 mg, 10.06 μmol) and (5S,7S,9S)-methyl9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(43.6 mg, 0.035 mmol). More DMF (134 μL) was added to dissolve bothreactants. The whole was purged with nitrogen gas, capped, and sonicatedfor 5 min. Then a freshly prepared solution of sodium ascorbate (100 mMin water, 40.2 μL, 4.02 μmol) followed by the addition of a freshlyprepared solution of copper sulfate pentahydrate (100 mM in water, 20.12μL, 2.01 μmol). The whole was purged with nitrogen gas, capped,sonicated for 5 min, and agitated on a shaker at rt. After 1.5 h LCMSshowed mainly both SMs but a lot of gummy solid adhered to the Eppendorfvial. More sodium ascorbate (100 mM in water, 80 μL, 8 μmol) and coppersulfate pentahydrate (100 mM in water, 40 μL, 4 μmol) were added. After15 min, the reaction was stopped. The whole was passed through an ISCOsolid loading filter plug with an aid of a vacuum. For the residue,dissolved with ˜0.5 mL of DMSO and passed through the same filter plug.The combined filtrate (1.7 mL) was purified by a reversed phasepreparative HPLC [Gradient 2] resulting in 2.12 mg, 4.47% yield of thetitle compound as a light yellow solid. ¹H NMR (400 MHz, DMSO-d₆) δ ppm9.32 (s, 1H) 8.63 (s, 1H) 8.56 (s, 2H) 7.98 (s, 2H) 7.69-7.85 (m, 1H)7.61 (br d, J=8.08 Hz, 1H) 7.32-7.49 (m, 1H) 7.16-7.32 (m, 1H) 6.85-7.13(m, 3H) 6.63 (br d, J=8.84 Hz, 1H) 6.44 (s, 1H) 6.19 (s, 1H) 5.76 (br s,1H) 5.63-5.73 (m, 1H) 5.49-5.63 (m, 1H) 5.39 (br d, J=7.58 Hz, 1H)4.37-4.67 (m, 9H) 3.87-4.15 (m, 7H) 3.74-3.87 (m, 6H) 3.71 (s, 5H) 3.63(br s, 5H) 3.41-3.57 (m, 26H) 3.21-3.27 (m, 1H) 3.00-3.21 (m, 4H) 2.89(br d, J=10.36 Hz, 1H) 2.70 (s, 4H) 2.63 (br d, J=14.15 Hz, 2H)2.53-2.58 (m, 1H) 2.29-2.40 (m, 3H) 1.86-2.03 (m, 1H) 1.59 (br dd,J=13.39, 7.33 Hz, 1H) 1.47 (dt, J=15.85, 7.61 Hz, 2H) 1.20-1.36 (m, 3H)1.16 (brd, J=7.83 Hz, 3H) 0.67-0.86 (m, 5H) 0.63 (br s, 1H) 0.45-0.58(m, 2H) 0.16 (s, 5H) 0.00-0.11 (m, 7H). MS (ES+): m/z=(M+3)/3=1571.9,(M+4)/4=1179.4, (M+5)/5=943.7, (M+6)/6=786.6; LCMS: t_(R)=1.58 min[polar_3 min_1500].

Compound 6

(S)-33-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oicAcid (6)

A solution oftert-butyl(S)-33-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(2.2 g, 2.095 mmol) in DCM (25 mL) was charged with trifluoroacetic acid(25 mL) and stirred at room temperature for 12 h. The reaction mixturewas concentrated in vacuo resulting in the crude compound. The crudecompound was purified by reverse phase combiflash column chromatography(acetonitrile:water: 0.1% TFA) to afford 91 mg, 4% yield of the titlecompound as a yellow solid. ¹H NMR (400 MHz, DMSO-d₆) δ=12.44 (br. s,2H), 11.56 (br. s, 2H), 8.71 (s, 1H), 8.20 (br. s, 1H), 7.96 (br. s,1H), 7.71 (d, J=8.31 Hz, 2H), 7.37 (br. s, 1H), 6.97-7.03 (m, 2H), 6.70(d, J=8.31 Hz, 2H), 4.55 (d, J=5.38 Hz, 1H), 4.31 (br. s, 1H), 4.18 (br.s, 4H), 3.71 (s, 4H), 3.35-3.65 (m, 31H), 3.23 (d, J=5.38 Hz, 2H),2.35-2.42 (m, 2H), 2.24 (d, J=6.36 Hz, 2H), 2.04-2.19 (m, 1H), 1.87-2.00(m, 1H), MS (ES⁺): m/z=994.55 [M+H]⁺; LCMS: t_(R)=2.23 min.

tert-Butyl(S)-33-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(13)

A solution oftert-butyl(S)-33-(4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzamido)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(2.9 g, 2.530 mmol) in DMF (25 mL) was charged with 0.1M solution ofpiperdine (50 mL) and stirred at room temperature for 3 h. The reactionmixture was concentrated in vacuo resulting in the crude compound. Thecrude compound was stirred in diethyl ether (40 mL) for 10 min and thesolid was filtered and washed with diethyl ether (20 mL) and dried toafford 2.2 g, 83% yield of the title compound as a yellow solid. ¹H NMR(400 MHz, DMSO-d₆) δ=8.64 (s, 1H), 8.17 (d, J=7.34 Hz, 1H), 7.95 (s,2H), 7.89 (t, J=5.38 Hz, 1H), 7.64 (d, J=8.80 Hz, 2H), 7.30 (s, 1H),6.89-6.94 (m, 2H), 6.64 (d, J=8.80 Hz, 2H), 4.48 (d, J=5.87 Hz, 2H),4.17-4.23 (m, 1H), 4.11 (d, J=1.47 Hz, 4H), 3.65 (s, 4H), 3.55 (t,J=6.36 Hz, 2H), 3.35-3.51 (m, 27H), 3.14-3.21 (m, 2H), 2.32 (t, J=6.11Hz, 2H), 2.19 (dd, J=7.09, 11.49 Hz, 2H), 1.81-2.03 (m, 2H), 1.44-1.61(m, 2H), 1.39 (s, 9H); MS (ES+): m/z=1050.00 [M]⁺; LCMS: t_(R)=1.90 min.

tert-Butyl(S)-33-(4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzamido)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(12)

A solution of 2,5-dioxopyrrolidin-1-yl4-(N-((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)-2,2,2-trifluoroacetamido)benzoate(1.5 g, 2.913 mmol) andtert-butyl(S)-33-amino-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(2.2 g, 2.913 mmol) in DMF (25 mL) was added DIPEA (1.01 mL, 5.826 mmol)under nitrogen atmosphere for 4 h. The reaction mixture was concentratedin vacuo resulting in the crude compound. The crude compound was stirredin diethyl ether (125 mL) for 15 min and the solid precipitated wasfiltered and washed with diethyl ether (50 mL) and dried to afford 3 g,90% yield, of the title compound as a yellow semisolid. ¹H NMR (400 MHz,DMSO-d₆) δ=11.42 (s, 2H), 8.76 (d, J=6.85 Hz, 1H), 8.62 (br. s, 1H),7.89 (d, J=7.34 Hz, 2H), 7.63 (d, J=7.82 Hz, 2H), 7.25-7.32 (m, 1H),6.79-7.08 (m, 2H), 4.20-4.30 (m, 1H), 4.04-4.14 (m, 6H), 3.65 (s, 4H),3.55 (t, J=6.11 Hz, 3H), 3.38-3.51 (m, 20H), 3.09-3.22 (m, 8H), 2.32 (t,J=5.87 Hz, 2H), 2.21 (d, J=6.36 Hz, 2H), 1.99-2.11 (m, 2H), 1.91 (dd,J=6.60, 14.43 Hz, 2H), 1.40 (s, 9H); MS (ES⁺): m/z=1146.63 [M+H]⁺; LCMS:t_(R)=2.64 min.

tert-Butyl(S)-33-amino-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(11)

A solution oftert-butyl(S)-33-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(3.8 g, 3.885 mmol) in diethyl amine (50 mL) was stirred at roomtemperature under nitrogen atmosphere for 12 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby flash column chromatography eluting with 0-15% methanol saturatedwith ammonia in DCM to afford 2.2 g, 75% yield, of the title compound asa colorless oil. ¹H NMR (400 MHz, CDCl₃) δ=4.15 (d, J=2.45 Hz, 6H), 3.83(s, 6H), 3.70-3.75 (m, 3H), 3.62-3.69 (m, 19H), 3.59 (t, J=5.14 Hz, 2H),3.48-3.50 (m, 2H), 3.42-3.47 (m, 2H), 2.80 (s, 6H), 2.42-2.49 (m, 6H),1.49 (s, 9H).

tert-Butyl(S)-33-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oate(10)

A solution of1-amino-N-(1,3-bis(prop-2-yn-1-yloxy)-2-((prop-2-yn-1-yloxy)methyl)propan-2-yl)-3,6,9,12,15,18-hexaoxahenicosan-21-amide(1.71 g, 4.035 mmol) in DCM (50 mL) was charged with(R)-4-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-5-(tert-butoxy)-5-oxopentanoicacid (2.3 g, 4.035 mmol), HATU (2.3 g, 6.052 mmol) and DIPEA (1.4 mL,8.070 mmol) and was stirred at room temperature for 16 h. The reactionmixture was diluted with water and extracted with ethyl acetate. Thecombined organic layers were dried over anhydrous Na₂SO₄, filtered andconcentrated in vacuo resulting in a crude compound which was purifiedby column chromatography on combiflash eluting with 0-5% methanol in DCMto afford 3.51 g, 89% yield, of the title compound as a yellow oil. ¹HNMR (400 MHz, CDCl₃) δ=7.76 (d, J=7.82 Hz, 2H), 7.59-7.64 (m, 2H),7.37-7.43 (m, 2H), 7.29-7.34 (m, 2H), 6.44 (br. s, 1H), 6.26 (br. s,1H), 5.74 (d, J=7.82 Hz, 1H), 4.39 (t, J=7.09 Hz, 2H), 4.23 (t, J=6.85Hz, 2H), 4.14 (d, J=1.96 Hz, 5H), 3.83 (s, 4H), 3.60-3.73 (m, 16H), 3.56(t, J=4.89 Hz, 2H), 3.39-3.48 (m, 2H), 3.17 (q, J=7.34 Hz, 1H), 2.80 (s,4H), 2.41-2.46 (m, 4H), 2.15-2.32 (m, 2H), 1.90-2.04 (m, 1H), 1.54-1.60(m, 6H), 1.47 (s, 9H); MS (ES⁺): m/z=978.58 [M+H]⁺; LCMS: t_(R)=3.24min.

1-Amino-N-(1,3-bis(prop-2-yn-1-yloxy)-2-((prop-2-yn-1-yloxy)methyl)propan-2-yl)-3,6,9,12,15,18-hexaoxahenicosan-21-amide(8)

A solution of1-azido-N-(1,3-bis(prop-2-yn-1-yloxy)-2-((prop-2-yn-1-yloxy)methyl)propan-2-yl)-3,6,9,12,15,18-hexaoxahenicosan-21-amide(3.2 g, 5.369 mmol) in THF: H₂O (4:1, 62.5 mL) was charged with TPP(4.22 g, 16.11 mmol) and was stirred at room temperature for 14 h. Thereaction mixture was concentrated in vacuo resulting in the crudecompound which was purified by column chromatography on silica geleluting with 0-10% methanol in DCM to afford 2.35 g, 77% yield, of thetitle compound as light yellow oil. ¹H NMR (400 MHz, CDCl₃) δ=6.37 (s,1H), 4.13-4.17 (m, 6H), 3.84 (s, 6H), 3.71 (t, J=5.87 Hz, 2H), 3.61-3.68(m, 23H), 3.48-3.53 (m, 2H), 2.86 (t, J=5.38 Hz, 2H), 2.43-2.46 (m, 4H).

1-Azido-N-(1,3-bis(prop-2-yn-1-yloxy)-2-((prop-2-yn-1-yloxy)methyl)propan-2-yl)-3,6,9,12,15,18-hexaoxahenicosan-21-amide(7)

A solution of 1-azido-3,6,9,12,15,18-hexaoxahenicosan-21-oic acid (2.6g, 6.860 mmol) in DCM (50 mL) was charged with oxalyl chloride (0.87 mL,10.29 mmol) and catalytic DMF (3 drops) and stirred at room temperaturefor 1 h. The reaction mixture was concentrated in vacuo resulting in thecrude intermediate acid chloride which was used directly withoutisolation for further reaction. To the resulting solution at 0° C. wasadded DIPEA (4.7 mL, 27.44 mmol) and1,3-bis(prop-2-yn-1-yloxy)-2-((prop-2-yn-1-yloxy)methyl)propan-2-amine(2.28 g, 6.860 mmol) and was stirred at room temperature for 2 h. Thereaction mixture was diluted with water and extracted with ethylacetate. The combined organic layers were dried over anhydrous Na₂SO₄,filtered and concentrated in vacuo to afford 3.6 g, 88% yield, of thetitle compound as a light yellow solid. ¹H NMR (400 MHz, CDCl₃) δ=6.59(s, 1H), 4.13-4.19 (m, 6H), 3.82-3.89 (m, 6H), 3.61-3.71 (m, 25H), 3.39(t, J=4.89 Hz, 2H), 2.43-2.48 (m, 2H), 1.47-1.52 (m, 2H).

1-Azido-3,6,9,12,15,18-hexaoxahenicosan-21-oic Acid (5)

A solution of ethyl 1-azido-3,6,9,12,15,18-hexaoxahenicosan-21-oate (5g, 12.27 mmol) in THF: H₂O (4:1, 40 mL) at 0° C. was charged withlithium hydroxide (1.47 g, 61.35 mmol) and stirred at room temperaturefor 2 h. The reaction mixture solvent was evaporated and the aqueouslayer was washed with DCM. The separated aqueous layer was acidifiedwith 2N HCl solution and extracted with 10% methanol in DCM. Thecombined organic layers were dried over anhydrous Na₂SO₄, filtered andconcentrated in vacuo resulting in the crude compound which was purifiedby column chromatography on silica gel eluting with 1-10% methanol inDCM to afford 3.8 g, 80% yield, of the title compound as a colorlessoil. ¹H NMR (400 MHz, CDCl₃) δ=3.79 (t, J=5.87 Hz, 2H), 3.63-3.71 (m,23H), 3.40 (t, J=4.89 Hz, 2H), 2.61 (t, J=5.87 Hz, 2H).

Ethyl 1-azido-3,6,9,12,15,18-hexaoxahenicosan-21-oate (4)

A solution of 17-azido-3,6,9,12,15-pentaoxaheptadecan-1-ol (10 g, 32.57mmol) in THF (100 mL) at 0° C. was charged with sodium hydride (1.94 g,48.85 mmol) over a period of 30 min. Followed by addition of ethyl3-bromopropanoate (5 mL, 39.08 mmol) at the same temperature and stirredfor 2 h. The reaction mixture was quenched with ammonium chloridesolution and extracted with ethyl acetate. The combined organic layerswere dried over anhydrous Na₂SO₄, filtered and concentrated in vacuoresulting in the crude compound which was purified by silica gel columnchromatography eluting with 1-3% methanol in DCM to afford 5.2 g, 40%yield, of the title compound as a colorless oil. 1H NMR (400 MHz, CDCl₃)δ=4.11-4.19 (m, 2H), 3.73-3.79 (m, 2H), 3.60-3.70 (m, 21H), 3.36-3.43(m, 2H), 2.56-2.62 (m, 2H), 1.26 (t, J=7.09 Hz, 3H).

17-Azido-3,6,9,12,15-pentaoxaheptadecan-1-ol (3)

A solution of 17-hydroxy-3,6,9,12,15-pentaoxaheptadecyl4-methylbenzenesulfonate (16 g, 36.69 mmol) in ethanol (200 mL) wascharged with sodium azide (7.15 g, 110.1 mmol) and heated at 80° C. for8 h. The reaction mixture was cooled to room temperature and the solventwas evaporated up to dryness. The residue obtained was stirred in ethylacetate, filtered and the filtrate was concentrated in vacuo resultingin 11.6 g of the crude compound as yellow oil. The crude compound wasused in the next step without further purification. ¹H NMR (400 MHz,CDCl₃) δ=3.59-3.77 (m, 23H), 3.37-3.41 (m, 2H).

17-Hydroxy-3,6,9,12,15-pentaoxaheptadecyl 4-methylbenzenesulfonate (2)

A solution of 3,6,9,12,15-pentaoxaheptadecane-1,17-diol (25 g, 88.59mmol) in DCM (900 mL) at 0° C. was charged with silver oxide (30.5 g,132.88 mmol), potassium iodide (2.94 g, 17.71 mmol) and tosyl chloride(18.51 g, 97.44 mmol) and stirred at 0° C. for 1 h. The reaction mixturewas filtered, washed with DCM and the filtrate was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 1-3% methanol in DCM to afford16 g, 41% yield of the title compound as a pale yellow oil. ¹H NMR (400MHz, CDCl₃) δ=7.80 (d, J=7.83 Hz, 2H), 7.34 (d, J=7.83 Hz, 2H),4.14-4.18 (m, 2H), 3.57-3.75 (m, 23H), 2.45 (s, 3H).

Example 73

tert-butyl(1,3-bis((4-(1-((2-(((3-(3-acetamidopropyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)-1H-1,2,3-triazol-4-yl)benzyl)oxy)-2-(((4-(1-((2-(((3-(3-acetamidopropyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)-1H-1,2,3-triazol-4-yl)benzyl)oxy)methyl)propan-2-yl)carbamate[Example 73]

A solution oftert-butyl(1,3-bis((4-ethynylbenzyl)oxy)-2-(((4-ethynylbenzyl)oxy)methyl) propan-2-yl)carbamate (10.00 mg, 0.018 mmol) andN-(3-(3-(((4-(azidomethyl) phenyl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide (22.59 mg, 0.055mmol) were dissolved in DMF (40.0 μl). The reaction mixture was chargedwith a solution of sodium ascorbate (1.757 mg, 8.87 μmol) in Water (80μl) followed by the addition of a solution of copper sulfatepentahydrate (2.78 mg, 8.87 μmol) in Water (80 μl). (NOTE: the reactionmixture formed turned brown upon addition of copper sulfate then turnedinto a yellow gel precipitate). After 5 min the reaction mixture waschecked by LCMS and found to have a mass consistent with desiredproduct. The reaction mixture was partitioned between DCM and water andseparated. The aqueous was extracted with DCM (3×) and the combinedorganic fractions were checked by LCMS and this showed a peak consistentwith product mass and a peak consistent with sm azide. The crude1 waspurified by ISCO chromatography on silica gel [4 g cartridge, elutingwith 0% of (10% NH₄OH in MeOH) in DCM to 8% of (10% NH₄OH in MeOH) inDCM] resulting in 12 mg, 37.5% yield of the title compound as a clearcolorless oil. ¹H NMR (CHLOROFORM-d, 400 MHz): δ (ppm) 8.59 (s, 6H),7.90 (s, 3H), 7.65-7.70 (m, 6H), 7.26-7.27 (m, 3H), 7.23-7.26 (m, 3H),5.64-5.72 (m, 2H), 5.55 (s, 6H), 4.49-4.53 (m, 6H), 3.75-3.81 (m, 6H),3.16-3.23 (m, 6H), 2.40 (s, 6H), 1.96 (s, 9H), 1.58 (s, 17H), 1.46-1.56(m, 6H), 1.43 (s, 9H), 0.47-0.57 (m, 5H), 0.21 (s, 18H), 0.08 (s, 18H),MS (ES⁺): 1802.66 m/z=[M+H]⁺; LCMS: t_(R)=2.55 min [polar_3 min_0_1500].

Compound 3

tert-butyl(1,3-bis((4-ethynylbenzyl)oxy)-2-(((4-ethynylbenzyl)oxy)methyl)propan-2-yl)carbamate(3)

A solution oftert-butyl(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)carbamate (800 mg,3.619 mmol) in DMF (5 mL) at 0° C. was charged with1-(bromomethyl)-4-ethynylbenzene 5 (4.21 g, 21.71 mmol) and powderedpotassium hydroxide (1.18 g, 21.71 mmol) portionwise over a period of 30min. The reaction mixture was allowed to attain room temperature andstirred for 14 h. The reaction mixture was diluted with water wasextracted with DCM. The combined organic layers were dried overanhydrous Na₂SO₄, filtered and concentrated in vacuo resulting in thecrude compound which was purified by column chromatography on silica geleluting with 0-5% methanol in DCM to afford 1.52 g, 75% yield, of thetitle compound as colorless oil. ¹H NMR (400 MHz, CDCl₃) δ=7.44 (d,J=7.82 Hz, 6H), 7.21 (d, J=7.82 Hz, 6H), 4.96 (s, 1H), 4.47-4.50 (m,6H), 3.76 (s, 6H), 3.07 (s, 3H), 1.41 (s, 9H); MS (ES⁺): m/z=564.55[M+H]⁺; LCMS: t_(R)=3.94 min.

1-(Bromomethyl)-4-ethynylbenzene (5)

A solution of triphenyl phosphine (11.8 g, 45.45 mmol) in DCM (100 mL)at 0° C. was charged with a solution of (4-ethynylphenyl)methanol (3 g,22.72 mmol), carbon tetrabromide (15 g, 45.45 mmol) and 2,6 lutidine(13.2 mL, 113.5 mmol) in DCM (mL). The reaction mixture allowed toattain room temperature and stirred for 16 h. The reaction mixture wasconcentrated in vacuo, diluted with diethyl ether and stirred for 15min. The solid precipitated out was filtered and the filtrate was washedwith 2N HCl solution and water. The separated organic layers were driedover anhydrous Na₂SO₄, filtered and concentrated in vacuo resulting inthe crude compound which was purified by column chromatography oncombiflash eluting with 0-5% ethyl acetate in n-hexane to afford 3 g(70% yield) of the title compound as yellow oil. ¹H NMR (400 MHz, CDCl₃)δ=7.46 (d, J=8.31 Hz, 2H), 7.35 (d, J=7.83 Hz, 2H), 4.47 (s, 2H), 3.10(s, 1H).

(4-Ethynylphenyl)methanol (4)

A solution of 4-ethynylbenzaldehyde (3.8 g, 29.23 mmol) in methanol (80mL) at 0° C. was charged with sodium borohydride (2.2 g, 58.46 mmol)portionwise. The reaction mixture allowed to attain room temperature andstirred for 2 h. The reaction mixture was concentrated in vacuo,quenched with saturated ammonium chloride solution and extracted withethyl acetate The combined organic layers were dried over anhydrousNa₂SO₄, filtered and concentrated in vacuo to afford 3.47 g, 90% yield,of the title compound as light yellow oil.

¹H NMR (400 MHz, CDCl₃) δ=7.49 (d, J=7.83 Hz, 2H), 7.33 (d, J=7.82 Hz,2H), 4.71 (s, 2H), 3.07 (s, 1H).

4-Ethynylbenzaldehyde (6)

A solution of 4-((trimethylsilyl)ethynyl)benzaldehyde (7.5 g, 37.12mmol) in methanol (100 mL) was charged with potassium carbonate (512 mg,3.712 mmol) and stirred at room temperature for 1 h. The reactionmixture was concentrated in vacuo, diluted with ethyl acetate andseparated organic layer was washed with water. The separated organiclayers were dried over anhydrous Na₂SO₄, filtered and concentrated invacuo resulting in the crude compound which was purified by columnchromatography on silica gel eluting with 0-20% ethyl acetate inn-hexane to afford 1.2 g, 81% yield, of the title compound as lightyellow solid. ¹H NMR (400 MHz, CDCl₃) δ=10.02 (s, 1H), 7.85 (d, J=7.83Hz, 2H), 7.64 (d, J=8.31 Hz, 2H), 3.30 (s, 1H).

4-((Trimethylsilyl)ethynyl)benzaldehyde (2)

A solution of 4-bromobenzaldehyde (10 g, 54.64 mmol) in diisopropylamine (500 mL) was charged with bis(triphenylphosphine)palladium(II)dichloride (380 mg, 0.546 mmol) and copper iodide (205 mg, 1.09 mmol)and degassed for 20 min. The reaction mixture was cooled to 0° C. andfollowed by dropwise addition of trimethyl silyl acetylene (11.2 mL,81.06 mmol) for a period of 30 min. The reaction mixture was allowed toattain room temperature and further refluxed for 3 h. The reactionmixture was cooled to room temperature and HBr salt formed was filtered.The filtrate was concentrated in vacuo, diluted with ethyl acetate andwashed with 1N HCl solution followed by saturated sodium bicarbonate andwater. The separated organic layers were dried over anhydrous Na₂SO₄,filtered and concentrated in vacuo resulting in the crude compound whichwas purified by column chromatography on silica gel eluting with 0-5%ethyl acetate in n-hexane to afford 7.7 g, 70% yield, of the titlecompound as an off white solid. ¹H NMR (400 MHz, CDCl₃) δ=10.00 (s, 1H),7.82 (d, J=8.31 Hz, 2H), 7.60 (d, J=7.83 Hz, 2H), 0.27 (s, 9H); MS(ES+): m/z=244.16 [M+H]⁺; LCMS: t_(R)=3.58 min.

tert-Butyl(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)carbamate (B)

A solution of Boc anhydride (81.2 mL, 619.0 mmol) in tert-butanol (150mL) was charged with a solution of2-amino-2-(hydroxymethyl)propane-1,3-diol A (50 g, 413.00 mmol) inmixture of tert-butanol:methanol (1:1, 250 mL) and stirred at roomtemperature for 24 h. The reaction mixture was concentrated in vacuo,resulting in the crude residue as white powder which was purified byrecrystallisation in ethanol to afford 45.6 g, 50% yield of the titlecompound as a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ=5.74 (s, 1H),4.45-4.51 (m, 3H), 3.52 (d, J=5.87 Hz, 6H), 1.37 (s, 9H).

Example 74

A solution ofN-(3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyl disiloxanyl)propyl)acetamide (15.93 mg, 0.039 mmol) in 0.766 mLof a 3:1 mixture of acetonitrile/water was charged with(1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethanol (5.8 mg, 0.039 mmol) andstirred overnight at rt. The crude reaction mixture was concentrated invacuo then purified by chromatography on silica gel, ISCO, 4 g goldcartridge [eluting with 100% DCM to 5% (10% 7N NH3 in MeOH) in DCM]resulting in 13.7 mg, 63% yield of the title compound as a thick clearcolorless oil. ¹H NMR (CHLOROFORM-d, 400 MHz): δ (ppm) 8.38 (s, 2H),5.60 (br s, 1H), 5.41 (s, 2H), 3.61-3.82 (m, 2H), 3.18-3.24 (m, 2H),3.09-3.17 (m, 1H), 2.80-2.97 (m, 2H), 2.63 (ddd, J=16.1, 10.5, 3.4 Hz,1H), 2.39 (s, 2H), 2.11-2.30 (m, 2H), 1.97 (s, 3H), 1.46-1.60 (m, 4H),1.41 (br s, 1H), 1.26 (s, 1H), 1.20 (dt, J=16.5, 8.4 Hz, 1H), 1.04 (dtd,J=10.8, 8.9, 5.1 Hz, 1H), 0.76-0.97 (m, 2H), 0.49-0.58 (m, 2H), 0.20 (s,6H), 0.08 (s, 6H), MS (ES+): m/z=563.45 [M+H]⁺; LCMS: t_(R)=1.93 min[polar_3 min_1500].

Example 75

(9H-fluoren-9-yl)methyl(3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy) ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate[Example 75]

A solution of mixture of1,3-bis(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(4.89 g, 6.459 mmol) and bis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(4.30 g, 6.459 mmol) in 4M HCl in dioxane (50 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 7 and 8. The mixture of intermediate7 and 8 was dissolved in acetonitrile (150 mL) and followed by additionof water (0.114 mL, 6.459 mmol), DIPEA (3.3 mL, 19.37 mmol) and stirredat room temperature for 1 h. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by combiflashcolumn chromatography on silica gel eluting with 70-100% ethyl acetatein n-hexane to afford 3.69 g, 82% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.56 (s, 2H), 7.88 (d, J=7.34Hz, 2H), 7.67 (d, J=7.34 Hz, 2H), 7.36-7.43 (m, 2H), 7.31 (t, J=7.34 Hz,2H), 7.27 (br. s, 1H), 4.45 (s, 2H), 4.27 (d, J=6.85 Hz, 2H), 4.20 (d,J=6.36 Hz, 1H), 3.51-3.60 (m, 10H), 3.34-3.39 (m, 2H), 2.90-2.98 (m,2H), 2.38 (s, 2H), 1.34-1.45 (m, 2H), 0.43-0.50 (m, 2H), 0.15 (s, 6H),0.05 (s, 6H); MS (ES⁺): m/z=725.51 [M+H]⁺; LCMS: t_(R)=3.97 min.

1,3-Bis(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(5)

A solution of 2-(2-(2-azidoethoxy)ethoxy)ethan-1-ol (2.3 g, 13.14 mmol)in THF (500 mL) at 0° C. was charged with sodium hydride (1.62 g, 39.42mmol) and stirred at the same temperature for 30 min. The reaction wasthen charged with1,3-bis(((5-(chloromethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(6.5 g, 13.14 mmol) and stirred at 0° C. 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby combiflash column chromatography on silica gel eluting with 0-5%methanol in DCM to afford 5.94 g, 60% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.57 (s, 4H), 4.57 (t, J=5.62Hz, 2H), 4.47 (s, 4H), 3.46-3.63 (m, 22H), 2.41 (s, 4H), 0.18 (s, 12H);MS (ES⁺): m/z=380.00 [M/2+H]⁺; LCMS: t_(R)=3.66 min.

Example 76

Methyl(3R,5S,7R,9S)-9-03aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate[Example 76]

A solution of (3R,5S,7R,9S)-methyl5-ethyl-9-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-5-(hydrazinecarbonyl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(200 mg, 0.260 mmol) in Acetonitrile (3.34 ml) and 1 M HCl in water(12.33 ml, 12.33 mmol) cooled to −10° C. then charged with solid sodiumnitrite (41.3 mg, 0.598 mmol). After 10 min the yellowish brown solutionwas adjusted to pH ˜8.00 dropwise adding cold sat NaHCO₃ solution (˜13.2mL of NaHCO₃ added). The solution was extracted rapidly with DCM (5×10mL) and the combined organic layers were washed with brine (1×20 mL) anddried over Na₂SO₄, filtered and concentrated to ˜8.00 mL-10 mL cooled to0° C. in and charged with a solution of3-(3-(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine(165 mg, 0.260 mmol) in 8.0 mL of DCM and allowed to stir at 0° C. for 2hr. The reaction mixture was concentrated in vacuo resulting in a lighttan solid. The crude was purified by chromatography on silica gel [ISCOCombiFlash, 12 g Gold cartridge, eluting with 0% of (10% 7N NH3 in MeOH)to 8% (10% 7N NH3 in MeOH) in DCM resulting in 137 mg, 38.4% yield ofthe title compound as a light orange foam solid. ¹H NMR (CHLOROFORM-d,400 MHz): δ (ppm) 9.54 (s, 1H), 8.50 (s, 2H), 8.04 (br s, 1H), 7.54 (d,J=8.1 Hz, 1H), 7.15-7.23 (m, 3H), 7.06-7.13 (m, 1H), 6.61 (s, 1H), 6.08(s, 1H), 5.83 (s, 2H), 4.51 (s, 2H), 4.18 (d, J=4.8 Hz, 1H), 3.90-4.03(m, 1H), 3.76-3.81 (m, 3H), 3.64-3.72 (m, 24H), 3.57-3.63 (m, 4H),3.37-3.41 (m, 3H), 3.18-3.35 (m, 6H), 3.09-3.16 (m, 2H), 2.79-2.90 (m,6H), 2.58-2.64 (m, 2H), 2.37-2.49 (m, 4H), 2.22-2.32 (m, 1H), 1.97-2.11(m, 1H), 1.69-1.83 (m, 2H), 1.17-1.66 (m, 13H), 0.86-1.00 (m, 7H), 0.84(br d, J=6.1 Hz, 1H), 0.53-0.62 (m, 2H), 0.17-0.24 (m, 6H), 0.10 (s,6H), MS (ES+): m/z=1371.50, 1372.57 [M+H]⁺; LCMS: t_(R)=1.63 min[polar_3 min_1500].

Example 77

2-(((3-(3-Acetamidopropyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)benzoicAcid [Example 78]

A solution of mixture of2-(((3-(chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)benzoicacid (1 g, 2.873 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide (954 mg, 2.873 mmol) in 4M HCl in dioxane (50 mL) wasstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude intermediates 5 and 6. Themixture of intermediate 5 and 6 was dissolved in acetonitrile (20 mL)and followed by addition of water (0.21 mL, 11.78 mmol) and DIPEA (3.1mL, 17.24 mmol) and stirred at room temperature for 1 h. The reactionmixture was concentrated in vacuo resulting in the crude compound whichwas purified by Combi Flash chromatography on silica gel eluting with0-10% methanol in DCM to afford 917 mg, 40% yield, of the title compoundas a colorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=12.86 (s, 1H), 7.83 (d,J=7.82 Hz, 1H), 7.74 (s, 1H), 7.43-7.53 (m, 2H), 7.13-7.18 (m, 1H),2.92-2.99 (m, 2H), 2.10 (s, 2H), 1.74 (s, 3H), 1.33-1.42 (m, 2H),0.45-0.51 (m, 2H), 0.18 (s, 6H), 0.06 (s, 6H), MS (ES⁺): m/z=400.10[M+H]⁺; LCMS: t_(R)=3.19 min.

2-(((3-(Chloromethyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)benzoicAcid [Example 92]

To a solution of 2-mercaptobenzoic acid (2 g, 12.98 mmol) in 1,4 dioxane(50 mL) was added triethyl amine (3.3 mL, 25.97 mmol) and1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisiloxane (5.9 g, 25.89 mmol)and stirred at room temperature for 4 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby Combi Flash column chromatography on silica gel eluting with 0-10%methanol in DCM to afford 1.80 g, 41% yield, of the title compound as awhite solid. ¹H NMR (400 MHz, DMSO-d₆) δ=12.92 (s, 1H), 7.88 (d, J=7.83Hz, 1H), 7.47-7.58 (m, 2H), 7.20 (t, J=7.34 Hz, 1H), 2.92 (s, 2H), 2.18(s, 2H), 0.25 (s, 6H), 0.21 (s, 6H), MS (ES⁺): m/z=224.95 monomer[M+H]⁺; LCMS: t_(R)=3.74 min.

Example 79

5-(N-((2-(((3-(3-(3-(((3S,8S,11S,14R)-1-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)phenyl)-3,14-dicarboxy-8-(carboxymethyl)-11-((3-(5,5-difluoro-7,9-dimethyl-5H-414,514-dipyrrolo[1,2-c:2′,1′-f][1,3,2]diazaborinin-3-yl)propanamido)methyl)-1,6,9,12-tetraoxo-2,7,10,13-tetraazapentadecan-15-yl)thio)-2,5-dioxopyrrolidin-1-yl)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate[Example 79]

A solution of5-(N-((2-(((3-(3-(3-(((3S,8S,11S,14R)-1-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)phenyl)-11-(aminomethyl)-3,14-dicarboxy-8-(carboxymethyl)-1,6,9,12-tetraoxo-2,7,10,13-tetraazapentadecan-15-yl)thio)-2,5-dioxopyrrolidin-1-yl)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(17.62 mg, 10.30 mmol) in DMF was added Bodipy NHS ester stirred at roomtemperature for 1 h. The TLC showed consumption of starting material.The reaction mixture was concentrated in vacuo resulting in the crudeintermediate and purified by triturating in acetonitrile to afford 35 mg(crude) of the title compound as violet solid. ¹H NMR (400 MHz, DMSO-d₆)δ=12.98 (s, 1H), 12.45 (s, 1H), 12.28 (s, 1H), 11.38 (s, 1H), 8.62 (br.s, 1H), 8.55 (s, 1H), 8.44 (br. s, 2H), 8.26 (s, 2H), 8.20 (d, J=6.36Hz, 1H), 8.16 (d, J=6.36 Hz, 1H), 8.01 (s, 2H), 7.85 (d, J=7.83 Hz, 2H),7.60-7.68 (m, 4H), 7.40 (d, J=7.34 Hz, 1H), 6.85-7.06 (m, 8H), 6.61 (d,J=7.34 Hz, 2H), 6.28 (d, J=19.56 Hz, 2H), 4.45 (br. s, 4H), 4.25-4.38(m, 4H), 4.13 (br. s, 2H), 3.98 (d, J=16.63 Hz, 2H), 3.55-3.70 (m, 8H),3.02-3.07 (m, 2H), 2.84-2.89 (m, 2H), 2.65 (br. s, 3H), 2.32 (d, J=10.27Hz, 4H), 2.22 (br. s, 6H), 1.82-2.11 (m, 8H), 1.42-1.46 (m, 2H),1.12-1.27 (m, 12H), 0.10 (br. s, 6H), 0.03 (br. s, 6H); MS (ES⁺):m/z=993.40 [M+H]⁺; LCMS: t_(R)=3.07 min.

5-(N-((2-(((3-(3-(3-(((3S,8S,11S,14R)-1-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)phenyl)-11-(aminomethyl)-3,14-dicarboxy-8-(carboxymethyl)-1,6,9,12-tetraoxo-2,7,10,13-tetraazapentadecan-15-yl)thio)-2,5-dioxopyrrolidin-1-yl)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)sulfamoyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(6)

To a solution of2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)-5-(N-((2-(((3-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)propyl)-1,1,3,3-tetramethyldisiloxanyl) methyl)thio)pyrimidin-5-yl)methyl)sulfamoyl)benzenesulfonate (10 mg, 0.01 mmol) andN5-((S)-1-(((S)-3-amino-1-(((R)-1-carboxy-2-(l1-sulfanyl)ethyl)amino)-1-oxopropan-2-yl)amino)-3-carboxy-1-oxopropan-2-yl)-N2-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzoyl)-L-glutamine (7.7 mg, 0.01 mmol) in DMF (1 mL) was added DIPEA(0.01 mL, 0.04 mmol) at room temperature and stirred for 1 h. Thereaction was monitored by LCMS (showed 80% desired product 6). Thereaction mixture was used as such in the next step without work-up. MS(ES⁺): m/z=857.15 [M/2+H]⁺; LCMS: t_(R)=2.47 min.

2-(6-(Diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)-5-(N-((2-(((3-(3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)sulfamoyl)benzenesulfonate(5a)

A solution of1-(3-(3-(((5-(aminomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)-1H-pyrrole-2,5-dione(300 mg, 0.707 mmol) in THF (10 mL) was added DIPEA (0.24 mL, 1.41 mmol)and5-(chlorosulfonyl)-2-(6-(diethylamino)-3-(diethyliminio)-3H-xanthen-9-yl)benzenesulfonate(408 mg, 0.707 mmol) at room temperature and stirred for 1 h. Thecompletion of reaction was monitored by TLC. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedcolumn chromatography on silica gel eluting with 0-10% methanol in DCMto afford 150 mg, 22% yield of the title compound as dark pink solid. MS(ES⁺): m/z=965.20 [M+H]⁺, 483.40 [M/2+H]⁺; LCMS: t_(R)=3.47 min.

1-(3-(3-(((5-(aminomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl) propyl)-1H-pyrrole-2,5-dione (4)

A solution of1-(3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)-1H-pyrrole-2,5-dione(750 mg, 1.66 mmol) in THF: H₂O (2.25:0.75 mL) was added TPP (1.3 g,4.99 mmol) and stirred at room temperature for 10 h. The completion ofreaction was monitored by TLC. The reaction mixture was concentrated invacuo resulting in the crude compound which was purified by columnchromatography on silica gel eluting with 0-10% methanol in DCM toafford 300 mg, 42% yield of the title compound as colorless oil. MS(ES⁺): m/z=424.67 [M+H]⁺

1-(3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)-1H-pyrrole-2,5-dione (3)

A solution of1,3-bis(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(1 g, 2.03 mmol) in 4M HCl in dioxane (20 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate Int-1. The crude intermediate Int-1(1.1 g, 4.02 mmol) was dissolved in acetonitrile (20 mL) and was added1-(3-(hydroxydimethylsilyl)propyl)-1H-pyrrole-2,5-dione 2 (865 mg, 4.06mmol) was added triethyl amine (1.09 mL, 8.05 mmol) and stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude compound which was purified by columnchromatography on silica gel eluting with 0-40% ethyl acetate inn-hexane to afford 750 mg, 82% yield of the title compound as acolorless oil. MS (ES⁺): m/z=450.66 [M+H]⁺.

Example 81

(2S,5S,8S,11S,14S,19S)-19-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-5,8,14-tris(carboxymethyl)-2-((1-((2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-03S,5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-11-(3-guanidinopropyl)-4,7,10,13,16-pentaoxo-3,6,9,12,15-pentaazaicosane-1,20-dioicAcid [Example 81]

To an Eppendorf vial, DMSO (1 mL) was added to a mixture of(2S,5S,8S,11S,14S,19S)-19-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-5,8,14-tris(carboxymethyl)-11-(3-guanidinopropyl)-4,7,10,13,16-pentaoxo-2-(prop-2-yn-1-yl)-3,6,9,12,15-pentaazaicosane-1,20-dioicacid (17.0 mg, 0.016 mmol) and(3R,5S,7R,9S)-methyl-9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(18.14 mg, 0.016 mmol) at rt. The vial was purged with nitrogen gas,capped, and sonicated for 5 min. Then a freshly prepared solution ofsodium ascorbate (100 mM in water 32.8 μL, 3.28 μmol) was added,followed by the addition of a freshly prepared solution of coppersulfate pentahydrate (100 mM in water, 32.8 μL, 3.28 μmol). The wholewas purged with nitrogen gas, capped, sonicated for 5 min, and agitatedon a shaker at rt. After 1 h, LCMS showed mainly product. The reactionwas stopped. The whole was passed through an ISCO solid loading filterplug with an aid of a vacuum. For the residue, dissolved with ˜0.5 mL ofDMSO and passed through the same filter plug. The combined filtrate (2mL) was purified by a reversed phase preparative HPLC [gradient 1]resulting in 10.3 mg, 29.3% yield of the title compound as a lightyellow solid after lyophilizing. ¹H NMR (400 MHz, DMSO-d₆) δ ppm8.52-8.70 (m, 4H) 8.45 (br s, 1H) 8.25 (br d, J=6.32 Hz, 1H) 8.17 (br s,1H) 7.98 (s, 1H) 7.72-7.90 (m, 2H) 7.63 (m, J=8.84 Hz, 2H) 7.54 (br s,1H) 7.35-7.43 (m, 1H) 7.12-7.33 (m, 2H) 6.85-7.11 (m, 6H) 6.62 (m,J=8.84 Hz, 2H) 6.43 (s, 1H) 6.20 (s, 1H) 5.68 (br dd, J=10.36, 5.56 Hz,1H) 5.48-5.61 (m, 3H) 4.53-4.79 (m, 2H) 4.42-4.53 (m, 3H) 4.25-4.41 (m,3H) 4.16 (br d, J=5.31 Hz, 2H) 3.94-4.10 (m, 3H) 3.89 (br s, 1H)3.74-3.85 (m, 3H) 3.62-3.74 (m, 5H) 3.51-3.62 (m, 7H) 3.03-3.33 (m, 36H)2.93 (br s, 4H) 2.64-2.78 (m, 7H) 2.53-2.64 (m, 2H) 2.21-2.47 (m, 10H)1.80-2.05 (m, 5H) 1.39-1.65 (m, 7H) 1.13-1.39 (m, 6H) 0.64-0.86 (m, 7H)0.44-0.61 (m, 2H) 0.16 (s, 6H) −0.03-0.14 (m, 8H), MS (ES⁺):m/z=[M+2]=1073.3, [M+3]/3=716.1, [M+4]/4=537.4; LCMS: t_(R)=1.74 min[polar_3 min_0_1500].

(2S,5S,8S,11S,14S,19S)-19-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-5,8,14-tris(carboxymethyl)-11-(3-guanidinopropyl)-4,7,10,13,16-pentaoxo-2-(prop-2-yn-1-yl)-3,6,9,12,15-pentaazaicosanedioicAcid (3)

The title compound was prepared by a similar solid phase synthetic routeusing L-propargyl lysine as described in these publications: (1) Viahov,Iontcho R., et al. “Design and regioselective synthesis of a newgeneration of targeted chemotherapeutics. Part 1: EC145, a folic acidconjugate of desacetylvinblastine monohydrazide.” Bioorganic & medicinalchemistry letters 16.19 (2006): 5093-5096. (2) Vlahov, Iontcho R., etal. “Design and regioselective synthesis of a new generation of targetedchemotherapeutics. Part II: Folic acid conjugates of tubulysins andtheir hydrazides:” Bioorganic & medicinal chemistry letters 18.16(2008): 4558-4561, ¹H NMR (400 MHz, DMSO-d₆) δ ppm 8.65 (s, 1H) 8.25 (brd, J=7.33 Hz, 1H) 8.04-8.18 (m, 4H) 7.95 (d, J=7.58 Hz, 1H) 7.82 (br d,J=7.83 Hz, 1H) 7.67 (d, J=8.84 Hz, 2H) 7.35 (br s, 1H) 6.96 (br s, 3H)6.65 (d, J=8.84 Hz, 3H) 4.45-4.66 (m, 6H) 4.15-4.36 (m, 4H) 3.04 (br d,J=6.57 Hz, 4H) 2.83-2.90 (m, 1H) 2.65-2.80 (m, 4H) 2.54-2.64 (m, 4H)2.31 (br t, J=7.96 Hz, 3H) 1.80-2.08 (m, 3H) 1.63-1.78 (m, 2H) 1.38-1.59(m, 4H). ¹⁹F NMR (400 MHz, DMSO-d₆) δ ppm −73.74. MS (ES⁺): m/z=1038.3[M+H]⁺, 520.0 [M+2H]⁺/2; LCMS: t_(R)=1.19 min [polar_3 min_1500].

Example 83

(31S)-31-(4-(((2-Amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-1-(1-((2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-((5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)-1H-1,2,3-triazol-4-yl)-4,4-bis(((1-((2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-((5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-1,4,5,6,7,8,9,10-octahydro-2H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)-1H-1,2,3-triazol-4-yl)methoxy)methyl)-6,28-dioxo-2,9,12,15,18,21,24-heptaoxa-5,27-diazadotriacontan-32-oicacid [Example 83]

To an Eppendorf vial, DMF (87 μL) was added to a mixture of(S)-33-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-8,30-dioxo-6,6-bis((prop-2-yn-1-yloxy)methyl)-4,11,14,17,20,23,26-heptaoxa-7,29-diazatetratriacont-1-yn-34-oicacid (6.50 mg, 6.54 μmol) and (3R,5S,7R,9S)-methyl9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(25.3 mg, 0.023 mmol). More DMF (87 μL) to dissolve both reactants. Thewhole was purged with nitrogen gas, capped, and sonicated for 5 min.Then a freshly prepared solution of sodium ascorbate (100 mM in water,26.2 μL, 2.62 μmol) followed by the addition of a freshly preparedsolution of copper sulfate pentahydrate (100 mM in water, 13.08 μL,1.308 μmol). The whole was purged with nitrogen gas, capped, sonicatedfor 5 min, and agitated on a shaker at rt for 1.5 h. The reaction wasincomplete therefore additional sodium ascorbate (100 mM in water, 4.02μL, 0.402 μmol) and copper sulfate pentahydrate (100 mM in water, 2.012μL, 0.201 μmol) were added to the reaction mixture and agitated on ashaker for 1 h. The whole was diluted with 1 mL DMSO and passed throughan ISCO solid loading filter plug with an aid of a vacuum. The residuewas dissolved with ˜0.3 mL of DMSO and passed through the same filterplug and the combined filtrate (1-2 mL) was purified by a reversed phasepreparative HPLC [gradient 2] resulting in 1.94 mg, 6.87% yield of thetitle compound as a light yellow solid. ¹H NMR (400 MHz, DMSO-d₆) δ ppm9.33 (s, 2H) 8.61-8.71 (m, 7H) 8.52 (br s, 2H) 8.16 (s, 3H) 7.97 (br s,1H) 7.77 (s, 3H) 7.57 (br s, 2H) 7.36 (br d, J=7.58 Hz, 3H) 7.26 (br d,J=7.83 Hz, 3H) 6.84-7.04 (m, 7H) 6.63 (d, J=8.59 Hz, 1H) 6.53-6.71 (m,1H) 6.56 (s, 1H) 6.44 (s, 2H) 6.19 (s, 2H) 5.50-5.80 (m, 11H) 4.40-4.52(m, 8H) 3.91-4.11 (m, 11H) 3.82 (br d, J=5.81 Hz, 2H) 3.71 (s, 15H)3.38-3.62 (m, 61H) 2.96-3.22 (m, 21H) 2.88 (br d, J=10.61 Hz, 4H)2.59-2.77 (m, 17H) 2.22-2.41 (m, 11H) 1.86-2.14 (m, 7H) 1.39-1.64 (m,12H) 1.10-1.37 (m, 28H) 0.67-0.90 (m, 21H) 0.63 (br s, 3H) 0.42-0.54 (m,6H) 0.15 (s, 18H) −0.02-0.08 (m, 21H), MS (ES⁺): m/z=[M+3]/3=1439.3,[M+4]/4=1080.4, [M+5]/5=864.4, [M+6]/6=720.5; LCMS: t_(R)=1.52 min[polar_3 min_0_1500]

Example 84

(24S)-24-(4-(((2-Amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-1-(1-(2-(2-(2-((2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-((5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methoxy)ethoxy)ethoxy)ethyl)-1H-1,2,3-triazol-4-yl)-21-oxo-2,5,8,11,14,17-hexaoxa-20-azapentacosan-25-oicAcid [Example 84]

Using a similar procedure as for Example 80, Example 84 was synthesizedusing, DMF (26 μL),(S)-26-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oicacid (2 mg, 2.69 μmol),(5S,7S,9S)-methyl9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-((2-(2-(2-azidoethoxy)ethoxy)ethoxy)methyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(5.01 mg, 4.04 μmol), sodium ascorbate (freshly prepared 100 mM inwater, 5.39 μl, 0.539 μmol), water (13.46 μL), copper sulfatepentahydrate (freshly prepared 100 mM in water, 2.69 μl, 0.269 μmol),and water (13.46 μL). The sample was purified by reverse phase HPLC[gradient 1] resulting in 1.29 mg, 24.2% yield of the title compound asa light yellow solid after lyophilization. LCMS using acidic mobilephase and method polar_3 min_0_1500 (0.8 mL/min flow) showed 98.0% pure(retention time=1.56 min) and confirmed title compound. ¹H NMR (400 MHz,DMSO-d₆) δ ppm 9.33 (s, 1H) 8.47-8.73 (m, 4H) 8.04 (s, 1H) 7.95 (br s,1H) 7.78 (s, 1H) 7.59 (br d, J=8.08 Hz, 2H) 7.37 (d, J=7.83 Hz, 1H) 7.26(d, J=8.34 Hz, 1H) 6.86-7.08 (m, 4H) 6.56-6.73 (m, 3H) 6.44 (s, 1H) 6.19(s, 1H) 5.50-5.78 (m, 2H) 4.39-4.58 (m, 9H) 3.67-4.03 (m, 13H) 3.42-3.62(m, 30H) 2.99-3.19 (m, 1H) 2.94-3.22 (m, 6H) 2.89 (br d, J=10.61 Hz, 1H)2.58-2.79 (m, 6H) 2.28-2.42 (m, 4H) 1.77-2.20 (m, 5H) 1.07-1.66 (m, 10H)0.58-0.89 (m, 7H) 0.52 (br d, J=7.58 Hz, 2H) 0.17 (s, 6H) 0.06 (s, 8H),MS (ES⁺): m/z=. [M+2]/2=992.2, [M+3]/3=661.8; LCMS: t_(R)=1.52 min[polar_3 min_0_1500]

Example 85

(2S,5S,8S,11S,14S,19S)-19-(4-(((2-Amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-5,8,14-tris(carboxymethyl)-2-((1-(1-(2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-05S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)-2,5,8,11,14,17-hexaoxanonadecan-19-yl)-1H-1,2,3-triazol-4-yl)methyl)-11-(3-guanidinopropyl)-4,7,10,13,16-pentaoxo-3,6,9,12,15-pentaazaicosane-1,20-dioicAcid [Example 85]

To an Eppendorf vial, DMSO (377 μL) was added to a mixture of(2S,5S,8S,11S,14S,19S)-19-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-5,8,14-tris(carboxymethyl)-11-(3-guanidinopropyl)-4,7,10,13,16-pentaoxo-2-(prop-2-yn-1-yl)-3,6,9,12,15-pentaazaicosane-1,20-dioicacid (15.66 mg, 0.015 mmol), and (5S,7S,9S)-methyl9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(20.7 mg, 0.015 mmol) at rt Immediately, solids precipitated out thesolution and the reaction mixture became green. The whole was purgedwith nitrogen gas, capped, and sonicated for 5 min. Then a freshlyprepared solution of sodium ascorbate (100 mM in water, 30.2 μL, 3.02μmol) followed by a freshly prepared solution of copper sulfatepentahydrate (100 mM in water, 15.09 μL, 1.509 μmol). The whole waspurged with nitrogen gas, capped, sonicated for 5 min, and agitated on ashaker at rt. A dark brown homogenous solution was formed. After 1 h,more sodium ascorbate (100 mM in water, 30.2 μL, 3.02 μmol) followed bycopper sulfate pentahydrate (100 mM in water, 15.09 μL, 1.509 μmol). Thereaction was incomplete therefore more alkyne SM (8 mg), sodiumascorbate (100 mM in water, 30.2 μL, 3.02 μmol), and copper sulfatepentahydrate (100 mM in water, 15.09 μL, 1.51 μmol) were added andagitated for another 1 h. The reaction was stopped and the whole wasdiluted with 1 mL DMSO and passed through an ISCO solid loading filterplug with an aid of a vacuum. The remaining residue was dissolved with˜0.3 mL of DMSO and passed through the same filter plug and the combinedfiltrate (2 mL) was purified by a reversed phase preparative HPLC[gradient 1] resulting in 9.55 mg, 26.3% yield of the title compound asa light yellow solid after lyophilization. ¹H NMR (400 MHz, DMSO-d₆) δppm 10.08 (br s, 1H) 9.34 (s, 1H) 8.55-8.68 (m, 3H) 8.15-8.54 (m, 5H)7.73-7.94 (m, 2H) 7.64 (br d, J=7.33 Hz, 2H) 7.51 (br s, 1H) 7.37 (br d,J=7.83 Hz, 1H) 7.26 (d, J=8.08 Hz, 1H) 6.87-7.18 (m, 5H) 6.62 (br d,J=8.08 Hz, 2H) 6.44 (s, 1H) 6.19 (s, 1H) 5.65-5.74 (m, 1H) 5.57 (br d,J=10.36 Hz, 1H) 4.25-4.65 (m, 10H) 3.92-4.20 (m, 2H) 3.67-3.89 (m, 11H)2.83-3.63 (m, 91H) 2.58-2.78 (m, 9H) 2.19-2.43 (m, 13H) 1.73-2.10 (m,9H) 1.10-1.66 (m, 16H) 0.59-0.85 (m, 7H) 0.45-0.56 (m, 2H) 0.17 (s, 6H)0.06 (s, 6H), MS (ES⁺): m/z=[M+2]/2=1206.4, [M+3]/3=804.2; LCMS:t_(R)=1.50 min [polar_3 min_0_1500]

Example 86

(24S)-24-(4-(((2-Amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-1-(1-(1-(2-(((3-(3-((3aR,3a1R,4R,5S,5aR,10bR)-3a-ethyl-9-((5S,7S,9S)-5-ethyl-5-hydroxy-9-(methoxycarbonyl)-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indol-9-yl)-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazole-5-carboxamido)propyl)-1,1,3,3-tetramethyldisiloxanyl)methy)thio)pyrimidin-5-yl)-2,5,8,11,14,17-hexaoxanonadecan-19-yl)-1H-1,2,3-triazol-4-yl)-21-oxo-2,5,8,11,14,17-hexaoxa-20-azapentacosan-25-oicacid [Example 86]

To an Eppendorf vial, DMSO (359 μL) was added into a mixture of(S)-26-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-23-oxo-4,7,10,13,16,19-hexaoxa-22-azaheptacos-1-yn-27-oicacid (12.0 mg, 0.016 mmol) and (5S,7S,9S)-methyl9-((3aR,3a1R,4R,5S,5aR,10bR)-5-((3-(3-(((5-(19-azido-2,5,8,11,14,17-hexaoxanonadecyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl) propyl)carbamoyl)-3a-ethyl-4,5-dihydroxy-8-methoxy-6-methyl-3a,3a1,4,5,5a,6,11,12-octahydro-1H-indolizino[8,1-cd]carbazol-9-yl)-5-ethyl-5-hydroxy-2,4,5,6,7,8,9,10-octahydro-1H-3,7-methano[1]azacycloundecino[5,4-b]indole-9-carboxylate(22.2 mg, 0.016 mmol). The whole was purged with nitrogen gas, capped,and sonicated for 5 min. Then a freshly prepared solution of sodiumascorbate (100 mM in water, 32.3 μL, 3.23 μmol) followed by a freshlyprepared solution of addition of copper sulfate pentahydrate (100 mM inwater, 16.2 μL, 1.62 μmol). A dark brown homogenous solution was formed.The whole was purged with nitrogen gas, capped, sonicated for 5 min, andagitated on a shaker at rt. After 1 h, more sodium ascorbate (100 mM inwater, 32.3 μL, 3.23 μmol) and copper sulfate pentahydrate (100 mM inwater, 16.2 μL, 1.62 μmol) were added. After 1 h, the reaction wasstopped. The whole was diluted with 2.5 mL DMSO and passed through anISCO solid loading filter plug with an aid of a vacuum and the residuewas dissolved with ˜0.3 mL of DMSO and passed through the same filterplug. The combined filtrate (3 mL) was purified by a reversed phasepreparative HPLC [gradient 1] resulting in 9.55 mg, 28.0% yield, of thetitle compound as a light yellow solid after lyophilization. ¹H NMR (400MHz, DMSO-d₆) δ ppm 8.64 (s, 1H) 8.58 (s, 2H) 8.04 (s, 1H) 7.64 (br d,J=8.34 Hz, 1H) 7.37 (d, J=8.08 Hz, 1H) 7.26 (d, J=7.83 Hz, 1H) 6.87-7.03(m, 4H) 6.64 (br d, J=8.59 Hz, 2H) 5.66-5.71 (m, 1H) 4.44-4.52 (m, 8H)3.89-4.09 (m, 3H) 3.69-3.84 (m, 8H) 3.65 (brd, J=9.09 Hz, 1H) 3.42-3.56(m, 49H) 3.01-3.26 (m, 6H) 2.90 (br d, J=17.18 Hz, 2H) 2.61-2.78 (m, 6H)2.30-2.46 (m, 4H) 2.17 (br s, 2H) 1.85-2.07 (m, 4H) 1.54-1.63 (m, 2H)1.48 (br dd, J=15.66, 7.83 Hz, 2H) 1.21-1.35 (m, 2H) 1.13-1.21 (m, 3H)0.70-0.84 (m, 6H) 0.64 (br s, 1H) 0.46-0.54 (m, 2H) 0.17 (s, 6H) 0.06(s, 7H), MS (ES⁺): m/z=[M+2]/2=1058.1, [M+3]/3=705.8; LCMS: t_(R)=1.57min [polar_3 min_0_1500].

Example 87

(2S,5S,8S,11S,14S,19S)-2-((1-((2-(((3-(3-Acetamidopropyl)-1,1,3,3-tetramethyldisiloxanyl)methyl)thio)pyrimidin-5-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-19-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-5,8,14-tris(carboxymethyl)-11-(3-guanidinopropyl)-4,7,10,13,16-pentaoxo-3,6,9,12,15-pentaazaicosane-1,20-dioicacid [Example 87]

To an Eppendorf vial, DMF (323 μL) was added into a mixture of(2S,5S,8S,11S,14S,19S)-19-(4-(((2-amino-4-oxo-3,4-dihydropteridin-6-yl)methyl)amino)benzamido)-5,8,14-tris(carboxymethyl)-11-(3-guanidinopropyl)-4,7,10,13,16-pentaoxo-2-(prop-2-yn-1-yl)-3,6,9,12,15-pentaazaicosane-1,20-dioicacid (32.7 mg, 0.032 mmol) andN-(3-(3-(((5-(azidomethyl)pyrimidin-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide(10 mg, 0.024 mmol). More DMF (323 μL) was added to dissolve alkyne SM.The whole was purged with nitrogen gas, capped, and sonicated for 5 min.Then a freshly prepared solution of sodium ascorbate (100 mM in water,48.5 μl, 4.85 μmol) in water (55 μL) followed by the addition of coppersulfate pentahydrate (100 mM in water, 48.5 μL, 4.85 μmol) in water (55μL). The whole was purged with nitrogen gas, capped, sonicated for 5min, and agitated on a shaker at rt. As the reaction proceeded, moresolids went into solution. After 2.5 h, the reaction was stopped. Thewhole was diluted with 1.5 mL DMSO and passed through an ISCO solidloading filter plug with an aid of a vacuum. The residue was dissolvedwith ˜0.5 mL of DMSO and passed through the same filter plug and thecombined filtrate (2 mL) was purified by a reversed phase preparativeHPLC [gradient 1] resulting in 6 mg, 17.1% yield, of the title compoundas a light yellow solid after lyophilization. ¹H NMR (400 MHz, DMSO-d₆)δ ppm 0.04 (s, 6H) 0.15 (s, 6H) 0.36-0.58 (m, 2H) 1.25-1.53 (m, 3H) 1.92(br s, 2H) 2.22-2.42 (m, 3H) 2.88-3.05 (m, 3H) 4.24-4.70 (m, 6H) 5.55(br s, 2H) 6.62 (br s, 2H) 6.86-7.30 (m, 4H) 7.35-7.72 (m, 3H) 7.75-8.09(m, 3H) 8.13-8.52 (m, 2H) 8.62 (br s, 4H) 10.07 (br s, 1H).(C57H79N21O19SSi2- calculated: 79 Hs, observed: 52 Hs, some may behidden in water peak or exchanging with water), MS (ES⁺): m/z=1451.3[M+2], 726.3 [M+2]/2; LCMS: t_(R)=1.53 min [polar_3 min_0_1500].

Example 88

N-(3-(1,1,3,3-Tetramethyl-3-(2-(pyrimidin-2-ylthio)ethyl)disiloxanyl)propyl)acetamide[Example 88]

A solution of mixture of2-((2-(1,1,3,3-tetramethyl-3-vinyldisiloxanyl)ethyl)thio)pyrimidine (500mg, 1.677 mmol) andN,N-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(570 mg, 1.677 mmol) in 4M HCl in dioxane (25 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 5 and 6. The mixture of intermediate5 and 6 was dissolved in acetonitrile (20 mL) and followed by additionof water (0.12 mL, 6.711 mmol) and DIPEA (1.85 mL, 10.06 mmol) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby Combi Flash chromatography on silica gel eluting with 0-10% methanolin DCM to afford 510 mg, 41% yield, of the title compound as a lightyellow oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.55 (d, J=4.89 Hz, 2H), 7.72(br. s, 1H), 7.09-7.15 (m, 1H), 3.04-3.11 (m, 2H), 2.88-2.96 (m, 2H),1.72 (s, 3H), 1.27-1.38 (m, 2H), 0.89-0.97 (m, 2H), 0.39-0.46 (m, 2H),0.05 (s, 6H), 0.00 (s, 6H); MS (ES⁺): m/z=372.10 [M+H]⁺; LCMS:t_(R)=3.20 min.

2-((2-(1,1,3,3-Tetramethyl-3-vinyldisiloxanyl)ethyl)thio)pyrimidine (3)

A solution of pyrimidine-2-thiol (1 g, 8.928 mmol) and1,1,3,3-tetramethyl-1,3-divinyldisiloxane (3.32 g, 17.85 mmol) in THF(50 mL) was added AIBN (146 mg, 0.892 mmol) and silica (100 mg, 10% w/w)at room temperature. The resulting solution was heated to reflux at 60°C. for 4 h. The reaction mixture was concentrated in vacuo resulting inthe crude compound which was purified by Combi Flash chromatography onsilica gel eluting with 0-100% ethyl acetate in n-hexane to afford 1 g,40% yield, of the title compound as a colorless oil. MS (ES⁺):m/z=299.05 [M+H]⁺; LCMS: t_(R)=3.71, 3.87 and 3.97 min.

Example 89 and Example 94

N-(3-(1,1,3,3-Tetramethyl-3-(3-(pyrimidin-2-ylthio)propyl)disiloxanyl)propyl)acetamide[Example 89]

A solution of mixture of1,1,3,3-tetramethyl-1,3-bis(3-(pyrimidin-2-ylthio)propyl)disiloxane (1g, 2.283 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide(757 mg, 2.283 mmol) in 4M HCl in dioxane (50 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 5 and 6. The mixture of intermediate5 and 6 was dissolved in acetonitrile (50 mL) and followed by additionof water (0.16 mL, 9.132 mmol) and DIPEA (2.4 mL, 13.69 mmol) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby Combi Flash chromatography on silica gel eluting with 0-10% methanolin DCM to afford 788 mg, 45% yield, of the title compound as a lightyellow oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.61 (d, J=4.89 Hz, 2H), 7.78(br. s, 1H), 7.19 (t, J=4.89 Hz, 1H), 3.10 (t, J=7.09 Hz, 2H), 2.95 (q,J=6.85 Hz, 2H), 1.77 (s, 3H), 1.63-1.73 (m, 2H), 1.29-1.40 (m, 2H),0.60-0.68 (m, 2H), 0.40-0.47 (m, 2H), 0.04 (s, 6H), 0.00 (s, 6H); MS(ES⁺): m/z=386.10 [M+H]⁺; LCMS: t_(R)=3.34 min.

1,1,3,3-Tetramethyl-1,3-bis(3-(pyrimidin-2-ylthio)propyl)disiloxane[Example 94]

A solution of pyrimidine-2-thiol (2 g, 17.85 mmol) in acetonitrile (50mL) was added potassium carbonate (7.39 g, 53.57 mmol) and1,3-bis(3-chloropropyl)-1,1,3,3-tetramethyldisiloxane (2.3 g, 8.035mmol) at room temperature and further heated to 60° C. for 4 h. Thereaction mixture was concentrated in vacuo, diluted with DCM and theinorganic material was filtered. The filtrate was concentrated in vacuoresulting in the crude compound which was purified by Combi Flashchromatography on silica gel eluting with 0-20% ethyl acetate inn-hexane to afford 2.3 g, 30% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=8.59 (d, J=4.89 Hz, 4H), 7.17(t, J=4.89 Hz, 2H), 3.06 (t, J=7.09 Hz, 4H), 1.60-1.70 (m, 4H),0.58-0.65 (m, 4H), 0.01 (s, 12H), MS (ES⁺): m/z=439.15 [M+H]⁺; LCMS:t_(R)=4.13 min.

Example 90 and Example 93

3-(3-(3-Azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)propan-1-amine[Example 90]

A solution of(9H-fluoren-9-yl)methyl(3-(3-(3-azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate (1 g, 2.016 mmol) in saturated ethanolic ammonia (50mL) was stirred at room temperature for 14 h. The reaction mixture wasconcentrated in vacuo and the crude compound was purified by Combi Flashchromatography on silica gel eluting with 0-10% methanol saturated withammonia in DCM to afford 375 mg, 68% yield, of the title compound as alight yellow oil. ¹H NMR (400 MHz, CDCl₃) δ=3.24 (t, J=6.85 Hz, 2H),2.67 (t, J=7.09 Hz, 2H), 1.57-1.66 (m, 2H), 1.40-1.49 (m, 4H), 0.48-0.59(m, 4H), 0.07 (s, 6H), 0.06 (s, 6H); MS (ES⁺): m/z=275.00 [M+H]⁺; LCMS:t_(R)=5.55 min.

(9H-Fluoren-9-yl)methyl(3-(3-(3-azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate [Example 93]

A mixture of 1,3-bis(3-azidopropyl)-1,1,3,3-tetramethyldisiloxane (1 g,3.333 mmol) andbis((9H-fluoren-9-yl)methyl)((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))dicarbamate(2.3 g, 3.333 mmol) in 4M HCl in dioxane (50 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 3 and 4. The mixture of intermediate3 and 4 was dissolved in acetonitrile (20 mL) and followed by additionof water (0.24 mL, 13.33 mmol) and DIPEA (3.7 mL, 19.99 mmol) andstirred at room temperature for 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby Combi Flash chromatography on silica gel eluting with 0-70% ethylacetate in n-hexane to afford 1.48 g, 45% yield, of the title compoundas a white solid. ¹H NMR (400 MHz, DMSO-d₆) δ=7.88 (d, J=7.34 Hz, 2H),7.67 (d, J=7.34 Hz, 2H), 7.37-7.45 (m, 2H), 7.24-7.35 (m, 3H), 4.28 (d,J=6.85 Hz, 2H), 4.20 (d, J=6.85 Hz, 1H), 3.26 (t, J=6.85 Hz, 2H), 2.94(q, J=6.68 Hz, 2H), 1.48-1.57 (m, 2H), 1.39 (td, J=7.64, 15.53 Hz, 2H),0.42-0.56 (m, 4H), 0.04 (s, 6H), 0.03 (s, 6H); MS (ES⁺): m/z=497.00[M+H]⁺; LCMS: t_(R)=4.58 min.

Example 95

N-(3-(3-(((1H-Benzo[d]imidazol-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)acetamide [Example 95]

A solution of1,3-bis(((1H-benzo[d]imidazol-2-yl)thio)methyl)-1,1,3,3-tetramethyldisiloxane(250 mg, 0.545 mmol) andN,N′-((1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-diyl))diacetamide1 (181 mg, 0.545 mmol) in 4M HCl in dioxane (20 mL) was stirred at roomtemperature for 1 h. The reaction mixture was concentrated in vacuoresulting in the crude intermediate 2 and 3. The mixture of intermediate2 and 3 was dissolved in acetonitrile (30 mL) and followed by additionof water (0.4 mL, 2.183 mmol) and DIPEA (0.6 mL, 3.275 mmol) and stirredat room temperature for another 1 h. The reaction mixture wasconcentrated in vacuo resulting in the crude compound which was purifiedby Combi Flash column chromatography on silica gel eluting with 0-5%methanol in DCM to afford 129 mg, 30% yield, of the title compound as acolorless oil. ¹H NMR (400 MHz, DMSO-d₆) δ=12.45 (s, 1H), 7.82 (br. s,1H), 7.47-7.51 (m, 1H), 7.32-7.37 (m, 1H), 7.07-7.13 (m, 2H), 2.99 (q,J=6.85 Hz, 2H), 2.57 (s, 2H), 1.78 (s, 3H), 1.36-1.46 (m, 2H), 0.48-0.54(m, 2H), 0.20 (s, 6H), 0.09 (s, 6H); MS (ES⁺): m/z=239.00 monomer[M+H]⁺; LCMS: t_(R)=1.65 min.

Example 96

(9H-Fluoren-9-yl)methyl(3-(3-(3-(4-benzyl-1H-1,2,3-triazol-1-yl)propyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate[Example 96]

To an Eppendorf vial, DMF (171 μL) was added to a mixture of(9H-fluoren-9-yl)methyl(3-(3-(3-azidopropyl)-1,1,3,3-tetramethyldisiloxanyl)propyl)carbamate(17 mg, 0.034 mmol) and 3-phenyl-1-propyne (5.11 mL, 0.041 mmol). MoreDMF (171 mL) was added to dissolve both reactants. The vial was purgedwith nitrogen gas, capped, and sonicated for 5 min Sodium ascorbate (100mM in water, 68.4 μL, 6.84 μmol) in water (171 μL) was added followed bythe addition of copper sulfate pentahydrate (100 mM in water, 34.2 μL,3.42 μmol) in water (171 μL). The vial was purged with nitrogen gas,capped, sonicated for 5 min, and agitated on a shaker at rt. A yellowsuspension was formed and after 5 min, the reaction was quenched withwater. The product was extracted with EtOAc (3×15 mL) and combinedorganic layers were dried over Na₂SO₄, filtered through a plug of glasswool, and concentrated in vacuo. The crude was purification by columnchromatography (solid loading) on silica gel [ISCO Combi-Flash, 4 gcartridge] eluting with 70:30 to 30:70 Hex:EtOAc afforded 8 mg, 38.1%yield, of the title compound as a colorless oil. LCMS (ESI+), 3 min run,20-90% gradient, retention time=2.45 m/z=613.51 [M+1]+. ¹H NMR (400 MHz,CHLOROFORM-d) δ ppm 0.05 (d, J=2.78 Hz, 10H) 0.19 (br d, J=2.53 Hz, 1H)0.44-0.55 (m, 4H) 0.80-0.97 (m, 1H) 1.13-1.38 (m, 2H) 1.40-1.54 (m, 2H)1.58 (s, 6H) 1.71-1.97 (m, 3H) 2.06 (s, 1H) 3.16 (q, J=6.57 Hz, 2H) 4.09(s, 2H) 4.17-4.32 (m, 3H) 4.40 (d, J=7.07 Hz, 2H) 5.06 (br s, 1H) 7.14(s, 1H) 7.19-7.34 (m, 7H) 7.40 (t, J=7.33 Hz, 2H) 7.53-7.68 (m, 2H) 7.77(d, J=7.58 Hz, 2H), MS (ES⁺): m/z=[M+2]/2=1058.1, [M+3]/3=705.8; LCMS:t_(R)=1.57 min [polar_3 min_0_1500].

Example 97: Synthesis of Conjugates

Conjugates are synthesized as exemplified in Schemes 1 and 2, below.Scheme 1 depicts a route where first a targeting moiety, folic acid, isactivated by reaction with DCC and N-hydroxysuccinimide and then reactedwith a protected siloxane or silylether core to form a targetingmoiety-core conjugate.

Scheme 2, below, shows an alternate route where a protected targetingmoiety-core conjugate is reacted with an activated payload to form atargeting moiety-core-payload conjugate.

Example 98: Vinblastine-Folic Acid Conjugates

Siloxane conjugates with a vinblastine payload and a folic acidtargeting moiety are synthesized following a route as described inExample 97.

Example 99: Vinblastine-Arginylglycylaspartic Acid (Vinblastine-RGD)Conjugate

Siloxane conjugates with vinblastine payload and a RGD targeting moietyare synthesized following a route as described in Example 97.

Example 100: Vinblastine-2-[3-(1,3-dicarboxypropyl)ureido]pentanedioicAcid (Vinblastine-DUPA) Conjugates

Siloxane conjugates with vinblastine payload and DUPA targeting moietyare synthesized following a route as described in Example 97.

Example 101: Camptothecin-Folic Acid Conjugates

Siloxane conjugates with camptothecin payload and folic acid-targetingmoiety are synthesized following a route as described in Example 97.

Example 102: Platinum(II)-Folic Acid and Platinum(IV)-DUPA AcidConjugates

Siloxane conjugates with platinum (II) and platinum (IV) payload andDUPA targeting moieties are synthesized following a route as describedin Example 97. These conjugates are pictured below.

Example 103: Fluorophore/Quencher-Folic Acid Conjugates

Siloxane conjugates with a fluorophor/quencher payload and folicacid-targeting moieties are synthesized following a route as describedin Example 97. These conjugates are pictured below.

Example 104: Fluorescein-Folic Acid Conjugates

Siloxane conjugates with a fluorescein payload and folic acid targetingmoieties are synthesized following a route as described in Example 97.These conjugates are pictured below.

Example 105: Silyldiether and Silylmonoether Conjugates

Silyldiether and silylmonoether conjugates with a payload and atargeting moiety are synthesized following a route as described inExample 97. These conjugates are pictured below.

Example 106: Paclitaxel-Folic Acid Conjugates

Siloxane conjugates with a paclitaxel payload and folic acid targetingmoiety are synthesized following a route as described in Example 97.These conjugates are pictured below.

Example 107: Hydrolysis Studies

Table 1 shows representative hydrolysis data of silicon-linkerconstructs and conjugates.

TABLE 1 T1/2 at pH T1/2 at pH Compound 7.4 (min) 5.0 (min) CommentsExample 1 >1440 100 ^(a) Example 7 >1440 20 ^(a) Example 8 1440 5 ^(a)Example 9 2400 25 ^(a) Example 10 35 35 ^(a) Example 15 >240 25 ^(a)Example 27 >120 12 ^(a) Example 28 ND >120 ^(a) Example 31 ND 30 ^(a)Example 34 >120 2 ^(a) Example 79 >1080 100 ^(a) Example 62 >180 20 ^(b)Example 63 >1080 60 ^(b) Example 69 >360 240 ^(b) Example 73 >1080 1080^(b) Example 80 1440 45 ^(b) Example 81 1440 35 ^(b) Example 82 >1440 60^(a) Example 83 >1440 NA ^(a) ^(a) experiment performed at 37° C. inHEPES buffer with 2% DMSO using water UPLC/MS. ^(b) experiment performedat 20° C. in HEPES buffer with 2% DMSO using water UPLC/MS.

Example 108: Imaging Study Demonstrating Endocytosis and Si—O Cleavage

Example 79 as shown above contains a folate receptor targeting ligand, aspacer moiety, a siloxane core and two different fluorescent dyes(BODIPY and rhodamine) positioned on either side of the siloxane core.Folate receptor alpha expressing KB cells were grown in folic acid freemedia. The cells were incubated for 30 minutes on ice with 50 nM ofExample 79, washed with fresh culture medium and then incubated in mediaat 37° C. for the desired length of time. The fate of both dyes wassimultaneously monitored using confocal microscopy using Zeiss LSM 780laser scanning microscope. Imaging studies revealed that at t=0 theintact Example 79 was bound to the folate receptor on the cell surfaceas visualized by colocalization of red and green signals and overlap offluorescent dyes on the cell surface, thereby showing FolateReceptors-specific binding of the silicon based conjugate. At t=30 min,endocytosis of intact Example 79 into the cell was observed asvisualized by BODIPY and rhodamine fluorescent signals and overlap ofdyes inside the cells (i.e., inside the endosomes). At t=30 min,cleavage of the siloxane core was observed as visualized by colorseparation of the two fluorescent dyes.

Example 109: Cellular Data

KB cells in culture were seeded in white clear bottom 96-well tissueculture plate at a density of 5,000 cells per well in a folate free RPMImedia with 10% FBS a day prior to compound addition. Cells were countedvisually with a hemocytometer and diluted accordingly to obtain thedesired density. Cells were allowed to incubate for 24 hours in ahumidified CO₂ atmosphere in an incubator at 37° C. The spent media wasaspirated and replenished with 100 μL of fresh media containing a 3-foldserial dilution of compound with concentrations ranging from 0.3 to 2000nM and with a final DMSO concentration of 0.1%. Blank wells withoutcompound were also treated with media containing 0.1% DMSO. Cells wereincubated for 2 h and washed 4 times with fresh media. The plates wereincubated for an additional 70 h in an incubator at 37° C. in 100 uLfresh folate free RPMI. At the end of 70 h, the spent media was removedand cells were washed once with fresh media and then suspended 100 μL ofPBS. 100 μL of constituted Cell titer-glo reagent was added to each welland luminescence was recorded with a VICTOR plate reader according tomanufacturers' protocol.

Table 2 shows EC50 values of siloxane based conjugates.

TABLE 2 Compound EC50 Example 80 ~265 nM Example 81 ~156 nM Example 82~193 nM

Table 3 shows percent cell kill with silicon based conjugates at 48 h.

TABLE 3 Compound % Kill (48 h) Example 80 84 Example 81 86 Example 82 80

Example 110: Synthetic Lethal Payload Combinations

Silicon based conjugates for treating VHL clear cell renal carcinoma viadelivery of synthetic lethal payload combinations include:

Silicon based conjugates for treating triple negative breast cancer viadelivery of synthetic lethal payload combinations using, for examplefolic acid as a targeting ligand include:

Silicon based conjugates for treating mutant KRAS cancers via, forexample, an EGFR-targeting approach include:

Example 111: Multiple Targeting Moieties

As described above, contemplated silicon based conjugates of thedisclosure may contain multiple targeting moieties to increase avidityby increasing the number of targeting moieties for binding to a cellsurface receptor. Targeting moieties are targeted toward cells, tissues,and organs shown in column 1 of Table 4. Targeting moieties are bound toreceptors shown in column 2 of Table 4 with bound targeting moietiesshown in brackets.

TABLE 4 Cells/Tissues/ Organs Receptor [Ligand] Brain Transporter at BBB[Chlorotoxin], transporter at BBB [(PhPro)₄] (SEQ ID NO: 1), LRP1[AngioPep], Kidney Folic acid receptor a [folate], megalin [(KKEEE)₃K](SEQ ID NO: 2), megalin [lysozyme], Liver Asialoglycoprotein receptorASGPR [Tris-GalNAc], LDLR [LDL] Bone Hydroxyapatite [bisphosphonate],Lung Delta-like protein-3 DLL3 receptor [DDL3 antibody] Bladder SLITRK6(SLITRK6-antibody) Intestine Orally dosed silicon based conjugates arecleaved in the gut to give silanols that travel to intestines where theyare absorbed and are active. Intestinal targets can be peripheryrestricted μ-opiod receptors [opiod PEG- silanols], chlorideion-channel, guanidine cyclase receptor [guanidine cyclase silanol]Cancer Folic acid receptor α [folate], prostate specific membraneantigen PSMA [DUPA], integrin α_(v)βv₃ receptor [RGD], receptordystroglycan [laminin, agrin, pikachurin, biglycan], cholescystokininreceptor CCKR [chloescystokinin antagonist], carbonic anhydrase IX(CAIX) [ carbonic anhydrase inhibitors], androgen receptor [androgenantagonist], estrogen receptor [estrogen antagonist, estradiol], CD206[humanized CD206 antibody], CD44 [hyaluronic acid, humanized CD44antibody], CD22 [anti-CD22 single chain variable fragment scFv), CD33[humanized anti- CD33 antibody], cMET receptor [cMET inhibitor], surfaceantigen in leukemia SAIL [SAIL antibody], Her-2 receptor [Herceptin],transferrin receptor TfR [transferrin mAb], glycoprotein NMB gpNMB[humanized anti-gpNMB monoclonal antibody], Trop-2[anti-Trop-2-antibody], luteinizing hormone- releasing hormone receptor[lutenizing hormone- releasing hormone], matrix metalloproteinase-2receptor MMP-2 [chlorotoxin CTX], HSP90 [HSP90 inhibitor], somatostatinreceptor (subtypes 2, 3 5) [somatostatin analogs: octreotide,lanreotide] Joints/Synovial Folic acid receptor a [folate], [albumin],CD44 Fluid [hyaluronic acid, humanized CD44 antibody], Macrophages CD206[CD206 antibody, Manocept], CD44 [hyaluronic acid, humanized CD44antibody], Dendritic cells NY-ESO-1 antigen [DEC205 mAb], LymphaticCD206 [CD206 antibody, Lymphoseek], system Muscular OCTN2 transportersSystem

Silicon based conjugates that bind to an integrin receptor include:

Silicon based conjugates having Tris-BPC-NeuAcα2-6Galβ1-4GlcNActargeting moieties that bind to CD22 receptor (Siglec-2), a regulator ofBCR signaling, include:

Silicon based conjugates having oligomeric saccharide of hyaluronic acidtargeting moieties that bind to CD44 receptor include:

Silicon based conjugates having folate targeting moieties that bind tofolate receptor include:

Silicon based conjugates having urea-based DUPA targeting moieties thatbind to PSMA (prostate specific membrane antigen) include:

Silicon based conjugates having Neurotensin (NT) triazole analogs thatbind to low density receptor-related protein 1 (LRP1) include:

Silicon based conjugates having Carbonic anhydrase IX targeting moietiesthat bind to Carbonic anhydrase IX (CALX) receptor include:

Silicon based conjugates having GalNAc (N-Acetyl-D-galactosamine)targeting moieties as homing agents for asialoglycoprotein-receptor inliver cells include:

Silicon based conjugates having bisphosphonate targeting moieties thattarget bone hydroxyapatite without receptor mediated endocytosisinclude:

Silicon based conjugates having mannose targeting moieties that bind toCD206 that is associated with positive disease-associated macrophagesinclude:

Silicon based conjugates having mixed CCKRb ligand and folate targetingmoieties that bind to CCKRb and folate receptors include:

Silicon based conjugates having mixed folate and anti-CD33 antibodytargeting moieties that bind to folate and CD33 receptors include:

Silicon based conjugates having mixed folate and RGD targeting moietiesthat bind to folate and integrin receptors include:

Silicon based conjugates having mixed somatostatin and anti-CD33antibody targeting moieties that bind G protein-coupled somatostatin andCD33 receptors include:

Example 112: Catalytic Moieties

As described above, contemplated silicon based conjugates of thedisclosure may contain one or more optional catalytic moietiescovalently bound directly or indirectly to the silicon-heteroatom core(e.g., a siloxane). In an embodiment, a disclosed catalytic moiety maybe divalent. In certain embodiments, a disclosed catalytic moiety ormoieties may be selected to optimize bond cleavage of a Si—O bond of asiloxane such that the payload moiety is released into the target cellor tissue. For example, a disclosed catalytic moiety or moieties may beselected to facilitate a pH-sensitive release of the payload moiety fromthe conjugate at pH less than about 7 or greater than about 7.5.Exemplary catalytic moieties may include, but are not limited to,monocyclic or bicyclic heteroaryl systems, for example, optionallysubstituted pyrroles, furans, thiophenes, imidazoles, pyrazoles,oxazoles, isoxazoles, thiazoles, isothiazoles, pyridines, pyrimidines,triazoles, tetrazoles, etc. For example, catalytic moieties may include,but are not limited to:

-   -   wherein R, R¹, R², R³ and R⁴ may be independently selected, for        each occurrence, from the group consisting of hydrogen,        C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl (or R¹ and R⁴, or R³ and R²,        taken together form a heterocycle; and Z¹, Z² and Z³ may be        independently selected, for each occurrence, from the group        consisting of a bond, C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl; and        wherein C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be optionally        substituted.

INCORPORATION BY REFERENCE

All publications and patents mentioned herein, including those itemslisted below, are hereby incorporated by reference in their entirety forall purposes as if each individual publication or patent wasspecifically and individually incorporated by reference. In case ofconflict, the present application, including any definitions herein,will control.

EQUIVALENTS

While specific embodiments have been discussed, the above specificationis illustrative and not restrictive. Many variations will becomeapparent to those skilled in the art upon review of this specification.The full scope of the embodiments should be determined by reference tothe claims, along with their full scope of equivalents, and thespecification, along with such variations.

Unless otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in this specification and attached claimsare approximations that may vary depending upon the desired propertiessought to be obtained.

What is claimed is:
 1. A silicon based conjugate having the formula:

and pharmaceutically acceptable salts thereof, wherein: L is a targetingmoiety that permits selective accumulation of the conjugate within atarget cell or tissue; A is an adaptor moiety selected from the groupconsisting of a carbon atom, a nitrogen atom, C₃₋₆cycloalkyl,C₃₋₆cycloalkenyl, phenyl, heteroaryl, and mono or bicyclic heterocyclyl;P is a payload moiety; R^(P) is P; Y¹ is represented by the formula:-LL²-G¹-LL³-; Y² is represented by the formula:-LL⁴-G²-LL⁵- n is an integer from 2 to 15; m is an integer from 1 to 12;at least one of G¹ and G² is a catalytic moiety, where at least one G¹or G² is a heteroaryl; G¹ and G² are independently selected for eachoccurrence from the group consisting of a bond, -heteroaryl-,—O-heteroaryl-, —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is0, 1, or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,—O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0, 1, or2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, —C(O)—C₀₋₆alkyl-,—C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-, —NR^(a)—C(O)—C₀₋₆alkyl-,—C(O)—NR^(a)—C₀₋₆alkyl-, and —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-,—O-heteroaryl-, —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is0, 1, or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,—O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0, 1, or2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may optionally besubstituted by one or more substituents selected from the groupconsisting of halogen, hydroxyl, cyano, C₁₋₆alkyl, C₁₋₆alkoxy, —COOH,—C(O)—O—C₁₋₆alkyl, —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,—C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b), —NR^(a)—SO₂—C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl; LL¹, LL², LL³, LL⁴ and LL⁵ arespacer moieties each independently selected for each occurrence from thegroup consisting of a bond and C₁₋₂₀alkylene, wherein one, two, three orfour methylene units of C₁₋₂₀alkylene are optionally and independentlyreplaced by C₃₋₈cycloalkylene, C₂₋₁₀alkenylene C₂₋₁₀alkynylene, aryl,heteroaryl, NR^(1Y)—, —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—, —C(O)—,—OC(O)—, —C(O)O—, —S—, —SO—, —SO₂—, —C(═S)—, —C(═NR^(1Y))—,—NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—; —(CH₂—CH₂—O)_(s)—, —(O—CH₂—CH₂)_(s)—, —NR^(1Y)—(CH₂—CH₂—O)_(s)—C₁₋₆alkyl-NR^(1Y)—C(O)—;—(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —S—C₀₋₆alkyl-; —NR^(1Y)—C₁₋₆alkyl-;—N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—; —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—;—SO₂—NR^(1Y)—C₀₋₆alkyl-; —N(R^(1Y))SO₂—C₀₋₆alkyl-;—SO₂-heterocyclyl-C₀₋₆alkyl-; -heterocyclyl-C(O)—;-heterocyclyl-C₀₋₆alkyl-NR^(1Y)—C(O)—;—NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;—O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;—O—C₁₋₆alkylene-; wherein, independently for each occurrence, R^(1Y) isselected from the group consisting of H, C₁₋₆alkyl, cycloalkyl,haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,heterobiaryl, mono or bicyclic heterocyclic, wherein the cycloalkyl,haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,heterobiaryl, mono or bicyclic heterocyclic are optionally substitutedwith one or more substituents selected from —COOH, urea, amidine,guanidine, sulfonamide, acylsulfonamide, and sulfonyl amide; s is aninteger from 1-15; R¹, R², R³, R⁴ are each methyl; and R^(a) and R^(b)are independently selected, for each occurrence, from the groupconsisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl; whereinC₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be optionally substituted; orR^(a) and R^(b), together with the nitrogen to which they are attached,form a 4-7 membered heterocyclic ring, optionally containing anadditional heteroatom selected from O, S, or N; wherein the 4-7 memberedheterocyclic ring is optionally substituted.
 2. The silicon basedconjugate of claim 1, wherein A is a carbon atom and n is
 3. 3. Asilicon based conjugate represented by the formula:

and pharmaceutically acceptable salts thereof, wherein: L is a targetingmoiety that permits selective accumulation of the conjugate within atarget cell or tissue; P is a payload moiety; Y¹ is represented by theformula:-LL²-G¹-LL³-; Y² is represented by the formula:-LL⁴-G²-LL⁵- at least one of G¹ and G² is a catalytic moiety, where atleast one G¹ or G² is a heteroaryl; G¹ and G² are independently selectedfor each occurrence from the group consisting of a bond, -heteroaryl-,—O-heteroaryl-, —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is0, 1, or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,—O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0, 1, or2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, —C(O)—C₀₋₆alkyl-,—C(O)—O—C₀₋₆alkyl-, —O—C(O)—C₀₋₆alkyl-, —NR^(a)—C(O)—C₀₋₆alkyl-,—C(O)—NR^(a)—C₀₋₆alkyl-, and —NR^(a)—C₀₋₆alkyl-; wherein -heteroaryl-,—O-heteroaryl-, —NR^(a)-heteroaryl-, —S(O)_(w)-heteroaryl- (wherein w is0, 1, or 2), —NR^(a)—SO₂-heteroaryl-, —SO₂—NR^(a)-heteroaryl-, -phenyl-,—O-phenyl-, —NR^(a)-phenyl-, —S(O)_(w)-phenyl- (wherein w is 0, 1, or2), —NR^(a)—SO₂-phenyl-, —SO₂—NR^(a)-phenyl-, may optionally besubstituted by one or more substituents selected from the groupconsisting of halogen, hydroxyl, cyano, C₁₋₆alkyl, C₁₋₆alkoxy, —COOH,—C(O)—O—C₁₋₆alkyl, —C(O)—NR^(a)R^(b), —NR^(a)—C(O)—C₁₋₆alkyl,—C(O)—NR^(a)—SO₂—C₁₋₆alkyl, —SO₃H, —SO₂—NR^(a)R^(b), —NR^(a)—SO₂—C₁₋₆alkyl, and —SO₂—NR^(a)—C₁₋₆alkyl; LL¹, LL², LL³, LL⁴ and LL⁵ arespacer moieties each independently selected for each occurrence from thegroup consisting of a bond and C₁₋₂₀alkylene, wherein one, two, three orfour methylene units of C₁₋₂₀alkylene are optionally and independentlyreplaced by C₃₋₈cycloalkylene, C₂₋₁₀alkenylene C₂₋₁₀alkynylene, aryl,heteroaryl, NR^(1Y)—, —N(R^(1Y))C(O)—, —C(O)N(R^(1Y))—, —O—, —C(O)—,—OC(O)—, —C(O)O—, —S—, —SO—, —SO₂—, —C(═S)—, —C(═NR^(1Y))—,—NR^(1Y)—C₁₋₁₅alkyl-NR^(1Y)—C(O)—; —(CH₂—CH₂—O)_(s)—, —(O—CH₂—CH₂)_(s)—, —NR^(1Y)—(CH₂—O)_(s)—C₁₋₆alkyl-NR^(Y1)—C(O)—;—(O—CH₂—CH₂)_(s)—NR^(1Y)—C(O)—; —S—C₀₋₆alkyl-; —NR^(1Y)—C₁₋₆alkyl-;—N(C₁₋₃alkyl)-C₁₋₆alkyl-NH—C(O)—; —NH—C₁₋₆alkyl-N(C₁₋₃alkyl)-C(O)—;—SO₂—NR^(1Y)—C₀₋₆alkyl-; —N(R^(1Y))SO₂—C₀₋₆alkyl-;—SO₂-heterocyclyl-C₀₋₆alkyl-; -heterocyclyl-C(O)—;-heterocyclyl-C₀₋₆alkyl-NR^(1Y)—C(O)—;—NR^(1Y)—C₀₋₆alkylene-heterocyclyl-C(O)—; —O—C₁₋₆alkylene-C(O)—;—O—C₁₋₁₅alkylene-NR^(1Y)—C(O)—; —O—C₁₋₁₅alkylene-C(O)—NR^(1Y)—;—O—C₁₋₆alkylene-; wherein, independently for each occurrence, R^(1Y) isselected from the group consisting of H, C₁₋₆alkyl, cycloalkyl,haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,heterobiaryl, mono or bicyclic heterocyclic, wherein the cycloalkyl,haloalkyl, halocycloalkyl, heteroalkyl, heterocycloalkyl,heterohaloalkyl, heterohalocycloalkyl, aryl, biaryl, heteroaryl,heterobiaryl, mono or bicyclic heterocyclic are optionally substitutedwith one or more substituents selected from —COOH, urea, amidine,guanidine, sulfonamide, acylsulfonamide, and sulfonyl amide; s is aninteger from 1-15; R¹, R², R³, R⁴ are each methyl; and R^(a) and R^(b)are independently selected, for each occurrence, from the groupconsisting of hydrogen, C₁₋₆alkyl, C₂₋₆alkenyl, and phenyl; whereinC₁₋₆alkyl, C₂₋₆alkenyl, and phenyl may be optionally substituted; orR^(a) and R^(b), together with the nitrogen to which they are attached,form a 4-7 membered heterocyclic ring, optionally containing anadditional heteroatom selected from O, S, or N; wherein the 4-7 memberedheterocyclic ring is optionally substituted.
 4. The silicon basedconjugate of claim 1, represented by the formula:

wherein G2 is a heteroaryl.
 5. The silicon based conjugate of claim 1,wherein P is selected independently for each occurrence to provide asynthetic lethal drug combination capable of effecting death of a targetcell having one or more gene mutations but not of a cell in which theone or more gene mutations are absent.
 6. The silicon based conjugate ofclaim 1, wherein P is selected independently for each occurrence toprovide a synthetic lethal drug combination capable of effecting deathof a diseased target tissue comprised of cells having one or more genemutations, but not of a tissue comprised of cells in which the one ormore gene mutations are absent.
 7. The silicon based conjugate of claim5, wherein the one or more mutations are associated with a cancerselected from the group consisting of renal carcinoma, mutant KRAScancer, and triple negative breast cancer.
 8. The silicon basedconjugate of claim 1, wherein the targeting moiety is capable of bindingto at least one of: an overexpressed intracellular target, a cellsurface receptor, a cognate ligand of a cell surface receptor, or a cellwall.
 9. The silicon based conjugate of claim 8, wherein the cognateligand of a cell surface receptor is a viral coat protein.
 10. Thesilicon based conjugate of claim 1, wherein the targeting moiety isselected from the group consisting of a small-molecule, a protein, anucleic acid, a lipid, an oligomer, a polysaccharide, a nanoparticle, anantibody, and an antibody fragment.
 11. The silicon based conjugate ofclaim 1, wherein the payload moiety is selected from the groupconsisting of a therapeutic agent, a diagnostic agent, an imaging agent,a photosensitizer, and a radiosensitizer.